Implement unifdef-all script

This script is useful for improving code readability when researching
code.  Do not commit results of this script.

scripts/unifdef-all.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+# This script uses unifdef to mass-remove code inside ifdefs, that are not
+# relevant to Linux.
+#
+# Use it only to improve readability when researching code.
+
+cd "$(git rev-parse --show-toplevel)" || exit
+
+git ls-files ./*.{h,cpp} | xargs unifdef \
+	-U WIN32 \
+	-U OS2 \
+	-U _WIN32 \
+	-U _WIN64 \
+	-U MACOSX \
+	-U C_DDRAW \
+	-m