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.
Makefiles simply need to use this value often, for better or for
worse.
(2) Create a new variable FIX_RPATH that lists variables that should
be cleansed of -R or -rpath values if ${_USE_RPATH} is "no". By
default, FIX_RPATH contains LIBS, X11_LDFLAGS, and LDFLAGS, and
additional variables may be appended from package Makefiles.
