Log Message:
Replace RPATH_FLAG with LINKER_RPATH_FLAG and COMPILER_RPATH_FLAG,
which are the full option names used to set rpath directives for the
linker and the compiler, respectively.  In places were we are invoking
the linker, use "${LINKER_RPATH_FLAG} <path>", where the space is
inserted in case the flag is a word, e.g. -rpath.  The default values
of *_RPATH_FLAG are set by the compiler/*.mk files, depending on the
compiler that you use.  They may be overridden on a ${OPSYS}-specific
basis by setting _OPSYS_LINKER_RPATH_FLAG and _OPSYS_COMPILER_RPATH_FLAG,
respectively.  Garbage-collect _OPSYS_RPATH_NAME and _COMPILER_LD_FLAG.