configure.ac: drop macro 'AC_PROG_CC_C99' from autoconf 2.70

The macro AC_PROG_CC_C99 has been obsoleted by autoconf 2.70 and
triggers a set of warnings from both 'aclocal' and 'autoconf'.
The test of AC_PROG_CC_C99 is now included in AC_PROG_CC.

For autoconf 2.69 and earlier the macro is still required, so
cannot be simply dropped.

Use a conditional test to avoid the warning on autoconf 2.70 but
still use AC_PROG_CC_C99 on older autoconf.

Change-Id: I5e8437f5a826fb63be6d07bcb5bb824f94683020
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/6009
Tested-by: jenkins
Reviewed-by: Marc Schink <dev@zapb.de>

diff --git a/configure.ac b/configure.ac
index 012486666d203f6f20ccc8e2ea0213a95ab84d31..6d0c7d096df6b8543386a674af762f15e206db38 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -25,7 +25,8 @@ AH_BOTTOM([
 
 AC_LANG([C])
 AC_PROG_CC
-AC_PROG_CC_C99
+# autoconf 2.70 obsoletes AC_PROG_CC_C99 and includes it in AC_PROG_CC
+m4_version_prereq([2.70],[],[AC_PROG_CC_C99])
 AM_PROG_CC_C_O
 AC_PROG_RANLIB
 PKG_PROG_PKG_CONFIG([0.23])