only add -mtune=native if it works

all

@@ -951,7 +951,9 @@ case "$cmd" in
 						[5-9]*|[1-9][0-9]*|4.[3-9]*|4.[1-9][0-9]*)
 							# gcc 4.3 or higher
 							# -march=native is broken < 4.3
-							export CC="$CC -mtune=native -march=native"
+							if $CC -mtune=native -march=native misc/tools/conftest.c -o conftest >/dev/null 2>&1; then
+								export CC="$CC -mtune=native -march=native"
+							fi
 							;;
 					esac
 					if [ -n "$WE_HATE_OUR_USERS" ]; then
@@ -1031,6 +1033,17 @@ case "$cmd" in
 			fi
 		fi
 
+		
+		if ! verbose $CC misc/tools/conftest.c -o conftest; then
+			msg ""
+			msg "COMPILER"
+			msg ""
+			msg "Y U NO COMPILE CODE?"
+			msg ""
+			exit 1
+		fi
+		rm -f conftest
+
 		verbose cd "$d0/d0_blind_id"
 		if ! $compiled0; then
 			# compilation of crypto library failed

misc/tools/conftest.c

@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+int main()
+{
+	printf("Hello, world!\n");
+	return 0;
+}