* cppexp.c: Don't include cpphash.h.
(parse_charconst, cpp_lex): Use cpp_defined.
(cpp_lex): Use get_directive_token throughout. Remove
unnecessary cases from switch. Move assertion-handling code
down to OTHER case.
(cpp_parse_expr): If we see '+' or '-', check the context to
determine if they are unary or binary operators. Streamline
the jumps a bit. Do not call skip_rest_of_line.
* cpplib.c: Make skip_rest_of_line and cpp_skip_hspace
static. Export get_directive_token. Update commentary.
(cpp_defined): New function.
(do_define): Remove reference to T_PCSTRING. Call
free_definition to release memory for old definition, when
redefining a macro.
(eval_if_expression): Set only_seen_white to 0 before calling
cpp_parse_expr. Call skip_rest_of_line after it returns.
(cpp_read_check_assertion): Don't preserve a pointer into the
token buffer across a call to cpp_get_token.
* Makefile.in (cppexp.o): Don't depend on cpphash.h.
* cppfiles.c (redundant_include_p): Use cpp_defined.
* cpphash.c (free_definition): New function.
(delete_macro): Use it. Update commentary.
* cpphash.h: Typedef HASHNODE here. Prototype cpp_lookup and
free_definition.
* cpplib.h: Don't typedef HASHNODE here. Delete T_PCSTRING
from enum node_type. Prototype cpp_defined and get_directive_token.
Don't prototype cpp_lookup, skip_rest_of_line, or cpp_skip_hspace.
* fix-header.c (check_macro_names): Use cpp_defined.
(read_scan_file): Set inhibit_warnings and inhibit_errors in
the options structure.