currently only Debug appends "d" so the Release and MinSizeWithDebInfo
(and MinSizeRel) all produce the same filenames. This set of changes
lets each build type have a cmake defined string appended, defaulting
to Release none, Debug d, RelWithDebInfo rd, MinSizeRel s. But a user
still can have Release, RelWithDebInfo, and MinSizeRel to produce the
same filenames. It does so by setting the preprocessor define
OSG_LIBRARY_POSTFIX in src/osgDB/CMakeLists.txt to one of the
previously defined cmake variables CMAKE_DEBUG_POSTFIX
CMAKE_RELEASE_POSTFIX CMAKE_RELWITHDEBINFO_POSTFIX
CMAKE_MINSIZEREL_POSTFIX. This method cuts down on the #ifdef _DEBUG
#else preprocessor directives in Registry.cpp as the extension is
always passed in OSG_LIBRARY_POSTFIX. That and __MINGW32__ didn't
have the _DEBUG check which looks like a bug."