Checks whether "-Wdelcaration-after-statement" is available in gcc before

trying to use it (simple shell script trick from Shin-Ichi).

src/test-option.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+echo 'main(){}' > dummy.c
+gcc $1 dummy.c > /dev/null 2>&1 && echo $1
+rm -f dummy.c a.out
+