cpphash.c: Move cpp_defined here from cpplib.c.

        * cpphash.c: Move cpp_defined here from cpplib.c.
        * cpplib.c: Update comments, move cpp_defined to cpphash.c.
        * cpplex.c (_cpp_lex_token): Don't leave the lexer at EOL.
        * cppmacro.c (cpp_get_token): Update comments, no need now
        to catch the CPP_EOF meaning EOL case.

From-SVN: r37345