Only use -flto=auto and -ffat-lto-objects if C compiler supports them.

configure

@@ -3306,7 +3306,6 @@ fi
 
 
 
-
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for sqrt in -lm" >&5
 $as_echo_n "checking for sqrt in -lm... " >&6; }
 if ${ac_cv_lib_m_sqrt+:} false; then :
@@ -3973,7 +3972,12 @@ fi
 
 
 if test "$GCC" = yes; then
-	CFLAGS="$CFLAGS -Wall -Wextra -Wstrict-prototypes -flto=auto -ffat-lto-objects"
+	CFLAGS="$CFLAGS -Wall -Wextra -Wstrict-prototypes"
+        # Check for link-time optimization support
+        for f in -flto=auto -ffat-lto-objects; do
+            echo -n "Checking if C compiler supports $f... "
+            if $CC -E $f /dev/null > /dev/null 2>&1 ; then echo "yes"; CFLAGS="$CFLAGS $f"; else echo "no"; fi
+        done
 fi
 
 if test "$ac_cv_perlartifacts" = "yes" ; then