Makefile.in (unlibsubdir): Define.

        * Makefile.in (unlibsubdir): Define.
        (DRIVER_DEFINES): Use unlibsubdir.
        (cccp.o, cpplib.o, protoize.o, unprotoize.o): Similarly.
        (stmp-fixinc): Similarly.
The infamous unlibsubdir patch.  Makes it somewhat easier to move toolchains
around.  Helps cygwin folks.

From-SVN: r22737