1. check that unused inline functions are removed
2. only allow compilation if they are or if the check if overridden
3. with CMAKE_GENERATOR=Makefiles, use all flags when testing
   (e.g. both CMAKE_C_FLAGS and CMAKE_C_FLAGS_DEBUG if
   CMAKE_BUILD_TYPE=Debug). This is because
 - on Solaris with the SunPro compiler, default CMAKE_C_FLAGS_xxx
   values contain -xO2 (for Release and RelWithDebInfo)
   and -g (for RelWithDebInfo and Debug)
 - proper inlining only works at -xO4 without -g
 - so if CMAKE_C_FLAGS has -xO4, inlining would work in
   configure.cmake (before this fix) and fail during actual compilation

also remove the outdated check for inline from myu_global.h