[glib/wip/lantw/check-getauxval-for-freebsd-12] gutils: Check whether getauxval function exists

[Ting-Wei Lan <lantw src gnome org>]

commit d216f1d0bb128b22c702df23bee77d97e2b6dfdd
Author: Ting-Wei Lan <lantw src gnome org>
Date:   Sun Oct 28 01:37:39 2018 +0800

    gutils: Check whether getauxval function exists
    
    FreeBSD 12 adds a new header, sys/auxv.h, to declare a function, elf_aux_info,
    for public use, which was considered an internal function in previous releases.
    This new function provides similar functionality with glibc getauxval, which is
    also declared in the same header, but their interfaces are not compatible. Since
    the only usage of sys/auxv.h is in g_check_setuid and FreeBSD already has
    issetugid to provide the required functionality, we fixes the compilation error
    by adding a check for getauxval function to prevent g_check_setuid from calling
    getauxval when sys/auxv.h is found but getauxval is not available.
    
    https://reviews.freebsd.org/D12743
    https://reviews.freebsd.org/rS324815

 configure.ac  | 1 +
 glib/gutils.c | 2 +-
 meson.build   | 1 +
 3 files changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/configure.ac b/configure.ac
index b69b27ca5..743840d1b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -862,6 +862,7 @@ AC_CHECK_FUNCS(getmntent_r setmntent endmntent hasmntopt getfsstat getvfsstat fa
 case $host_os in aix*) ac_cv_func_splice=no ;; esac # AIX splice() is something else
 AC_CHECK_FUNCS(splice)
 AC_CHECK_FUNCS(prlimit)
+AC_CHECK_FUNCS(getauxval)
 
 # To avoid finding a compatibility unusable statfs, which typically
 # successfully compiles, but warns to use the newer statvfs interface:
diff --git a/glib/gutils.c b/glib/gutils.c
index 2b750aba9..e86aeca32 100644
--- a/glib/gutils.c
+++ b/glib/gutils.c
@@ -2503,7 +2503,7 @@ const gchar *g_get_tmp_dir_utf8 (void) { return g_get_tmp_dir (); }
 gboolean
 g_check_setuid (void)
 {
-#if defined(HAVE_SYS_AUXV_H)
+#if defined(HAVE_SYS_AUXV_H) && defined(HAVE_GETAUXVAL) && defined(AT_SECURE)
   unsigned long value;
   int errsv;
 
diff --git a/meson.build b/meson.build
index f2ffd9919..e642ae227 100644
--- a/meson.build
+++ b/meson.build
@@ -397,6 +397,7 @@ functions = [
   'fchown',
   'fdwalk',
   'fsync',
+  'getauxval',
   'getc_unlocked',
   'getfsstat',
   'getgrgid_r',