Convert some case problems with minGW at CI-time

.travis/script_mingw.sh

@@ -3,6 +3,11 @@
 set -ex
 . .travis/docker_container.sh
 
+# need to convert some includes to lower case (as of VST 3.7.1)
+find vst/external/VST_SDK -type d -name source -exec \
+     find {} -type f -name '*.[hc]' -o -name '*.[hc]pp' -print0 \; | \
+  xargs -0 sed -i 's/<Windows.h>/<windows.h>/'
+
 mkdir -p build/${INSTALL_DIR} && cd build
 if [[ ${CROSS_COMPILE} == "mingw32" ]]; then
   buildenv i686-w64-mingw32-cmake -DCMAKE_BUILD_TYPE=Release \