enable optional verbose output

[darealshinji]

building with make, make VERBOSE= or make VERBOSE=0 won't change anything, but setting VERBOSE to anything else will show the output that goes into the build log

Please read http://mxe.cc/#creating-packages

In particular, make sure that your build rules:

• install .pc file,
• install bin/test-pkg.exe compiled with flags by pkg-config,
• install .dll to bin/ and .a, .dll.a to lib/,
• use $(TARGET)-cmake instead of cmake,
• build in $(BUILD_DIR) instead of $(SOURCE_DIR),
• do not run target executables with Wine,
• do not download anything while building,
• do not install documentation,
• do not install .exe files except test and build systems,

and .patch files are generated by tools/patch-tool-mxe.

If you add a package, you can use tool tools/skeleton.py.

Thanks!