c-common.c: Convert to using ctype macros defined in system.h.

c-common.c: Convert to using ctype macros defined in system.h.

        * c-common.c: Convert to using ctype macros defined in system.h.
        * c-lex.c: Likewise.
        * cccp.c: Likewise.
        * collect2.c: Likewise.
        * rs6000.c: Likewise.
        * cpplib.c: Likewise.
        * fix-header.c: Likewise.
        * gcc.c: Likewise.
        * gen-protos.c: Likewise.
        * pexecute.c: Likewise.
        * protoize.c: Likewise.
        * rtl.c: Likewise.
        * scan.c: Likewise.
        * stmt.c: Likewise.
        * tlink.c: Likewise.
        * toplev.c: Likewise.

From-SVN: r19579