use the pedantically correct compiler for preprocessing
diff --git a/busybox.sh b/busybox.sh
index 7c3deb2..9ab0f4b 100755
--- a/busybox.sh
+++ b/busybox.sh
@@ -4,7 +4,7 @@
 export LC_CTYPE=POSIX
 
 RAW=` \
-    gcc -E -dM ${1:-Config.h} | \
+    $CC -E -dM ${1:-Config.h} | \
     sed -n -e '/^.*BB_FEATURE.*$/d;s/^#define.*\<BB_\(.*\)\>/\1.c/gp;' \
     | tr A-Z a-z | sort
 `