* cppinit.c (cpp_create_reader): Initialize
discard_comments_in_macro_exp.
(COMMAND_LINE_OPTIONS): Add "-CC" option.
(cpp_handle_option): Handle "-CC" option.
* cpplex.c (save_comment): If saving a C++ comment in
a directive, convert it to a C comment.
(_cpp_lex_direct): Pass second comment start character to
save_comment to indicate comment type.
* cpplib.c (_cpp_handle_directive): If processing
a "#define" directive and discard_comments_in_macro_exp
is false,  re-enable saving of comments.
(lex_macro_node): If discard_comments_in_macro_exp is false,
discard any comments before the macro identifier.
* cpplib.h (struct cpp_options): Add discard_comments_in_macro_exp
member.
* cppmacro.c (cpp_get_token): If expanding a macro while
processing a directive, discard any comments we might encounter.
(parse_params): If discard_comments_in_macro_exp is false,
ignore comments in the macro parameter list.
* gcc.c (cpp_unique_options): Add "-CC" option.
(option_map): Map "--comments-in-macros" to "-CC".
* doc/cppopts.texi: Document "-CC" option.
* f/lang-specs.h: Add "-CC" option.
* testsuite/gcc.dg/cpp/maccom1.c: New test.
* testsuite/gcc.dg/cpp/maccom2.c: New test.
* testsuite/gcc.dg/cpp/maccom3.c: New test.
* testsuite/gcc.dg/cpp/maccom4.c: New test.
* testsuite/gcc.dg/cpp/maccom5.c: New test.
* testsuite/gcc.dg/cpp/maccom6.c: New test.

From-SVN: r51975