Update mingw-w64 to the latest version

This fixes a few headers as necessary for building asan, and
fixes cross compiling widl.

build-mingw-w64.sh

@@ -21,7 +21,7 @@ cd mingw-w64
 
 if [ -n "$SYNC" ] || [ -n "$CHECKOUT" ]; then
     [ -z "$SYNC" ] || git fetch
-    git checkout 55e067dc48ad4aededf7a858b15a3039e8088ed4
+    git checkout 1b29d1bc58910a4c21ff2c5c804bf06821032348
 fi
 
 cd mingw-w64-headers