Fix mapping for <bits/syscall.h>

SYS_xxx macros, which are implemented in glibc in
<bits/syscall.h>, are intended to be included from
<sys/syscall.h>.  See syscall(2), amd also see the following:

$ grepc -k 'SYS_[a-z]\w+' /usr/include | head
/usr/include/x86_64-linux-gnu/bits/syscall.h:35:# define SYS_accept __NR_accept
/usr/include/x86_64-linux-gnu/bits/syscall.h:39:# define SYS_accept4 __NR_accept4
/usr/include/x86_64-linux-gnu/bits/syscall.h:43:# define SYS_access __NR_access
/usr/include/x86_64-linux-gnu/bits/syscall.h:47:# define SYS_acct __NR_acct
/usr/include/x86_64-linux-gnu/bits/syscall.h:51:# define SYS_acl_get __NR_acl_get
/usr/include/x86_64-linux-gnu/bits/syscall.h:55:# define SYS_acl_set __NR_acl_set
/usr/include/x86_64-linux-gnu/bits/syscall.h:59:# define SYS_add_key __NR_add_key
/usr/include/x86_64-linux-gnu/bits/syscall.h:63:# define SYS_adjtimex __NR_adjtimex
/usr/include/x86_64-linux-gnu/bits/syscall.h:67:# define SYS_afs_syscall __NR_afs_syscall
/usr/include/x86_64-linux-gnu/bits/syscall.h:71:# define SYS_alarm __NR_alarm
$ grep -rn bits/syscall.h /usr/include
/usr/include/x86_64-linux-gnu/bits/syscall.h:5:# error "Never use <bits/syscall.h> directly; include <sys/syscall.h> instead."
/usr/include/x86_64-linux-gnu/sys/syscall.h:27:   programs expect the traditional form SYS_*.  <bits/syscall.h>
/usr/include/x86_64-linux-gnu/sys/syscall.h:29:#include <bits/syscall.h>

I removed duplicate mappings, and also removed the mapping for
<syscall.h>, which is an undocumented feature of glibc.  Portable
programs should stick to <sys/syscall.h> (and unportable ones
too, since there's no gain apart from those 4 bytes).

Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>

gcc.libc.imp

@@ -91,7 +91,7 @@
   { include: [ "<bits/string3.h>", private, "<string.h>", public ] },
   { include: [ "<bits/stropts.h>", private, "<stropts.h>", public ] },
   { include: [ "<bits/sys_errlist.h>", private, "<stdio.h>", public ] },
-  { include: [ "<bits/syscall.h>", private, "<sys/syscall.h>", private ] },
+  { include: [ "<bits/syscall.h>", private, "<sys/syscall.h>", public ] },
   { include: [ "<bits/sysctl.h>", private, "<sys/sysctl.h>", public ] },
   { include: [ "<bits/syslog-ldbl.h>", private, "<sys/syslog.h>", private ] },
   { include: [ "<bits/syslog-path.h>", private, "<sys/syslog.h>", private ] },
@@ -169,7 +169,6 @@
   { include: [ "<bits/string.h>", private, "<string.h>", public ] },
   { include: [ "<bits/string2.h>", private, "<string.h>", public ] },
   { include: [ "<bits/string3.h>", private, "<string.h>", public ] },
-  { include: [ "<bits/syscall.h>", private, "<sys/syscall.h>", private ] },
   { include: [ "<bits/timerfd.h>", private, "<sys/timerfd.h>", public ] },
   { include: [ "<bits/typesizes.h>", private, "<sys/types.h>", public ] },
   # Top-level #includes that just forward to another file:
@@ -180,7 +179,6 @@
   # to decide which of the two files is canonical.  If neither is
   # on the POSIX.1 1998 list, I just choose the top-level one.
   { include: [ "<sys/poll.h>", private, "<poll.h>", public ] },
-  { include: [ "<sys/syscall.h>", private, "<syscall.h>", public ] },
   { include: [ "<sys/syslog.h>", private, "<syslog.h>", public ] },
   { include: [ "<sys/ustat.h>", private, "<ustat.h>", public ] },
   { include: [ "<wait.h>", private, "<sys/wait.h>", public ] },
@@ -202,7 +200,7 @@
   { include: [ "<asm/errno.h>", private, "<errno.h>", public ] },
   { include: [ "<asm/errno-base.h>", private, "<errno.h>", public ] },
   { include: [ "<asm/ptrace-abi.h>", private, "<asm/ptrace.h>", public ] },
-  { include: [ "<asm/unistd.h>", private, "<syscall.h>", public ] },
+  { include: [ "<asm/unistd.h>", private, "<sys/syscall.h>", public ] },
   { include: [ "<linux/limits.h>", private, "<limits.h>", public ] },   # PATH_MAX
   { include: [ "<linux/prctl.h>", private, "<sys/prctl.h>", public ] },
   { include: [ "<sys/ucontext.h>", private, "<ucontext.h>", public ] },

iwyu_include_picker.cc

@@ -460,7 +460,7 @@ const IncludeMapEntry libc_include_map[] = {
   { "<bits/string3.h>", kPrivate, "<string.h>", kPublic },
   { "<bits/stropts.h>", kPrivate, "<stropts.h>", kPublic },
   { "<bits/sys_errlist.h>", kPrivate, "<stdio.h>", kPublic },
-  { "<bits/syscall.h>", kPrivate, "<sys/syscall.h>", kPrivate },
+  { "<bits/syscall.h>", kPrivate, "<sys/syscall.h>", kPublic },
   { "<bits/sysctl.h>", kPrivate, "<sys/sysctl.h>", kPublic },
   { "<bits/syslog-ldbl.h>", kPrivate, "<sys/syslog.h>", kPrivate },
   { "<bits/syslog-path.h>", kPrivate, "<sys/syslog.h>", kPrivate },
@@ -538,7 +538,6 @@ const IncludeMapEntry libc_include_map[] = {
   { "<bits/string.h>", kPrivate, "<string.h>", kPublic },
   { "<bits/string2.h>", kPrivate, "<string.h>", kPublic },
   { "<bits/string3.h>", kPrivate, "<string.h>", kPublic },
-  { "<bits/syscall.h>", kPrivate, "<sys/syscall.h>", kPrivate },
   { "<bits/timerfd.h>", kPrivate, "<sys/timerfd.h>", kPublic },
   { "<bits/typesizes.h>", kPrivate, "<sys/types.h>", kPublic },
   // Top-level #includes that just forward to another file:
@@ -549,7 +548,6 @@ const IncludeMapEntry libc_include_map[] = {
   // to decide which of the two files is canonical.  If neither is
   // on the POSIX.1 1998 list, I just choose the top-level one.
   { "<sys/poll.h>", kPrivate, "<poll.h>", kPublic },
-  { "<sys/syscall.h>", kPrivate, "<syscall.h>", kPublic },
   { "<sys/syslog.h>", kPrivate, "<syslog.h>", kPublic },
   { "<sys/ustat.h>", kPrivate, "<ustat.h>", kPublic },
   { "<wait.h>", kPrivate, "<sys/wait.h>", kPublic },
@@ -571,7 +569,7 @@ const IncludeMapEntry libc_include_map[] = {
   { "<asm/errno.h>", kPrivate, "<errno.h>", kPublic },
   { "<asm/errno-base.h>", kPrivate, "<errno.h>", kPublic },
   { "<asm/ptrace-abi.h>", kPrivate, "<asm/ptrace.h>", kPublic },
-  { "<asm/unistd.h>", kPrivate, "<syscall.h>", kPublic },
+  { "<asm/unistd.h>", kPrivate, "<sys/syscall.h>", kPublic },
   { "<linux/limits.h>", kPrivate, "<limits.h>", kPublic },   // PATH_MAX
   { "<linux/prctl.h>", kPrivate, "<sys/prctl.h>", kPublic },
   { "<sys/ucontext.h>", kPrivate, "<ucontext.h>", kPublic },