* c-common.h (warn_cast_qual, warn_missing_format_attribute,
warn_pointer_arith, warn_missing_prototypes, warn_parentheses,
warn_missing_braces, warn_sign_compare, warn_long_long,
warn_redundant_decls, warn_float_equal, warn_char_subscripts,
warn_conversion, warn_format_y2k, warn_format_extra_args,
warn_format_zero_length, warn_format_nonliteral,
warn_format_security, mesg_implicit_function_declaration,
warn_bad_function_cast, warn_traditional,
warn_declaration_after_statement, warn_strict_prototypes,
warn_missing_declarations, warn_nested_externs,
warn_sequence_point, warn_init_self, warn_div_by_zero,
warn_implicit_int, warn_nonnull, warn_old_style_definition,
warn_selector, warn_undeclared_selector, warn_protocol,
warn_abi, warn_invalid_offsetof, warn_ctor_dtor_privacy,
warn_overloaded_virtual, warn_nonvdtor, warn_reorder,
warn_synth, warn_pmf2ptr, warn_ecpp, warn_sign_promo,
warn_old_style_cast, warn_nontemplate_friend,
warn_deprecated): Remove explicit declarations.
* c-common.c: Likewise, remove explicit definitions.
* c-opts.c: Likewise, remove explicit assignments.
* c.opts: Likewise, add implicit declare/define/assign.

From-SVN: r83680