Use modern C and use int main(void) { return 0; } as a compiler test.

No need to bump revision since this fails hard with ports-gcc.

games/oilwar/patches/patch-configure

@@ -0,0 +1,12 @@
+Index: configure
+--- configure.orig
++++ configure
+@@ -1036,7 +1036,7 @@ cat > conftest.$ac_ext << EOF
+ #line 1037 "configure"
+ #include "confdefs.h"
+ 
+-main(){return(0);}
++int main(void){return(0);}
+ EOF
+ if { (eval echo configure:1042: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+   ac_cv_prog_cc_works=yes