* c-common.c (unsigned_conversion_warning): Move warning control
from if() to warning(OPT_*).
(c_common_truthvalue_conversion): Likewise.
(c_do_switch_warnings): Likewise.
* c-decl.c (diagnose_mismatched_decls): Likewise.
(diagnose_mismatched_decls): Likewise.
(define_label): Likewise.
(grokdeclarator): Likewise.
* c-format.c (check_format_info): Likewise.
* c-lex.c (interpret_integer): Likwise.
(lex_string): Likewise.
* c-opts.c (c_common_post_options): Likewise.
* c-parser.c (c_parser_unary_expression): Likewise.
* c-pragma.c (handle_pragma_redefine_extname): Likewise.
(handle_pragma_extern_prefix): Likewise.
* c-typeck.c (build_binary_op): Likewise.
* gcse.c (is_too_expensive): Likewise.
* opts.c (decode_options): Likewise.
* stor-layout.c (place_field): Likewise.
* tree-cfg.c (remove_bb): Likewise.

* c.opt (-Wreturn-type): Add Var(warn_return_type).
* flags.h (warn_return_type): Remove.
* toplev.c (warn_return_type): Likewise.

From-SVN: r100135