tccpp: macro cleanup

tccpp: macro cleanup

- remove TOK_NOSUBST, mark the token itself instead
- get_tok_str(); mask out SYM_FIELD & update uses
- next(): optimize (~5% faster with tcc -E)
- tok_flags: remove some redundancy
- parse_define(): do not remove spaces around '##' and after '#'
    and mark macros with '##' as MACRO_JOIN to avoid unnecessary
    call to macro_twosharps(mstr):
- next_nomacro(): removed, next_nomacro1(): renamed to next_nomacro()
- next_argstream(): cleanup & new function peek_file()
- macro_subst_tok(): handle special macros (__DATE__ etc.)
  like normal macros if they are #defined
- -DPP_DEBUG : more structured output
- pp_error(): better preprocessor expression error message
- tcctok.h: sort basic keywords (somehow)
- testspp/Makefile: generate .expect with 'make testspp.##+'
- tcc.c: tcc -E -o file : put unixy LFs also on windows