The source project of this merge request has been removed.
Add cmake c/cxx/ld flags parameter and export it for compile and link
we have to export CFLAGS/CXXFLAGS/LDFLAGS if using a multi gcc environment, so I add --cmake_c_flags/c_compiler/cxx_flags/cxx_compiler/ld_flags to bootstrapt, so we can build it with the parameter above instead of export it manually, export the flags may interfere the others.