Basic stdenv for mingw. No compiler yet and setup needs more fixing.

svn path=/nixpkgs/trunk/; revision=6124

pkgs/stdenv/mingw/builder.sh

@@ -0,0 +1,9 @@
+source $STDENV/setup
+source $SUBSTITUTE
+
+mkdir $OUT
+
+substitute "$SETUP" "$OUT/setup" \
+    --subst-var INITIALPATH \
+    --subst-var GCC \
+    --subst-var SHELL