cpp.texi: Update for -MQ.

        * cpp.texi: Update for -MQ.
        * cppinit.c (cpp_create_reader): Always create pfile->deps.
        (cpp_cleanup): Always free pfile->deps.
        (initialize_dependency_output): Don't create pfile->deps.
        (cpp_handle_option): Similarly.
        (OPT_MQ): New.
        * gcc.c (cpp_options): Handle -MQ.
        (DEFAULT_WORD_SWITCH_TAKES_ARG): Add -MQ.
        * mkdeps.c (base_name): Remove.
        (deps_init): Don't allocate vector space until it's needed.
        (deps_free): Only free vectors if allocated.
        (deps_add_target, deps_add_dep): Update for initial allocation.
        (deps_add_default_target): Don't strip to the base_name.

From-SVN: r38735