Switch ANGLE to release mode

[treeswift]

The present ANGLE integration builds it in debug mode.
Upon troubleshooting major ANGLE use cases, it should be switched to release (-DCMAKE_BUILD_TYPE=DEBUG removed).

Originally posted by @treeswift in #11 (comment)

[pahaze]

Sounds good, but maybe we should make a switchable build type for it when it's ready to be used in Release mode? Just for any other/new issues that arise. Maybe like making two targets. One being angle.mk and the other being angle-debug.mk and on complete build, the opposite build type's "install" file is removed from usr/armv7-w64-mingw32/installed/angle*. Basically installing angle-debug will remove ANGLE as Release (if installed) and the "install" file (usr/armv7-w64-mingw32/installed/angle), then install ANGLE as Debug, or vice versa.

[treeswift]

What's the standard way of building components in debug mode in mxe? (Ideally, avoiding full dependent tree rebuilding if the rebuilt artifacts are shared libraries.)

[pahaze]

There isn't one 😂