[PATCH] extern-inline: Pull __header_inline definition

[Roman Bolshakov]

* m4/extern-inline.m4 (gl_EXTERN_INLINE): __header_inline is defined in
  <sys/cdefs.h> but the header is not included and as result
  _GL_EXTERN_INLINE doesn't work as intended on macOS.

Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
---
Hi,

The issue prevents -O1/-O0 compilation of libtasn1 on macOS:
https://gitlab.com/gnutls/libtasn1/-/issues/28#note_505357689

Thanks,
Roman

 m4/extern-inline.m4 | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/m4/extern-inline.m4 b/m4/extern-inline.m4
index a2acf126c..b2ac5e0fe 100644
--- a/m4/extern-inline.m4
+++ b/m4/extern-inline.m4
@@ -7,6 +7,8 @@ dnl with or without modifications, as long as this notice is 
preserved.
 
 AC_DEFUN([gl_EXTERN_INLINE],
 [
+  AC_CHECK_HEADERS_ONCE([sys/cdefs.h])
+
   AH_VERBATIM([extern_inline],
 [/* Please see the Gnulib manual for how to use these macros.
 
@@ -51,6 +53,12 @@ AC_DEFUN([gl_EXTERN_INLINE],
      warning: to disable this warning use -fgnu89-inline or the gnu_inline 
function attribute
    It defines a macro __GNUC_GNU_INLINE__ to indicate this situation.
  */
+
+/* Pull __header_inline definition */
+#ifdef HAVE_SYS_CDEFS_H
+# include <sys/cdefs.h>
+#endif
+
 #if (((defined __APPLE__ && defined __MACH__) \
       || defined __DragonFly__ || defined __FreeBSD__) \
      && (defined __header_inline \
-- 
2.30.0