Allow configure.ac to be processed by autoconf 2.69.

AC_PROG_CC_STDC is deprecated in autoconf 2.70 and above but it is
necessary for autoconf 2.69.

configure

@@ -18851,6 +18851,7 @@ then :
 
 fi
 
+
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for an ANSI C-conforming const" >&5
 printf %s "checking for an ANSI C-conforming const... " >&6; }
 if test ${ac_cv_c_const+y}
@@ -22264,7 +22265,8 @@ fi
 
 else case e in #(
   e)
-																					     ;;
+																						:
+	     ;;
 esac
 fi
 

configure.ac

@@ -17,7 +17,7 @@ dnl WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 dnl ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 dnl OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 dnl
-AC_PREREQ([2.70])
+AC_PREREQ([2.69])
 AC_INIT([sudo], [1.9.13], [https://bugzilla.sudo.ws/], [sudo])
 AC_CONFIG_HEADERS([config.h pathnames.h])
 AC_CONFIG_SRCDIR([src/sudo.c])
@@ -2383,7 +2383,9 @@ AS_IF([test -n "$with_libraries"], [
 
 dnl
 dnl C compiler checks (to be done after os checks)
+dnl AC_PROG_CC_STDC is deprecated in autoconf 2.70 and above.
 dnl
+m4_case(m4_defn([AC_AUTOCONF_VERSION]), [2.69*], [AC_PROG_CC_STDC])
 AC_C_CONST
 AC_C_INLINE
 AC_C_VOLATILE
@@ -2676,6 +2678,7 @@ AC_CHECK_FUNCS([getgrouplist], [], [
 		dnl	AC_DEFINE([HAVE___NSS_INITF_GROUP])
 		dnl    ])
 		dnl])
+		:
 	    ])
 	])
 	;;