- configure/Makefiles: minor adjustments

- build-tcc.bat: add -static to gcc options
  (avoids libgcc_s*.dll dependency with some mingw versions)

- tccpe.c/tcctools.c: eliminate MAX_PATH
  (not available for cross compilers)

- tccasm.c: use uint64_t/strtoull in unary()
  (unsigned long sometimes is only uint32_t, as always on windows)

- tccgen.c: Revert (f077d16c) "tccgen: gen_cast: cast FLOAT to DOUBLE"
  Was a rather experimental, tentative commit, not really necessary
  and somewhat ugly too.

- cleanup recent osx support:
  - Makefile/libtcc.c: cleanup copy&paste code
  - tccpp.c: restore deleted function