Made separate CONLYFLAGS  for C-specific (not CPP) flags.  -Wno-pointer-sign causes an error on C++ targets
each module exports library directory and library dependency file as symbols following the naming convention x_LIB_DIR and x_LIB_DEP.  The library files are used to create a LIB_DEPS symbol in modules that perform a link (bootloader/main).  This fixes the problem where a change is made in a dependency module, but not linked in the final executable (libs were not part of the dependency chain for the link recipe.)