usage:
    tcc -ar [rcsv] lib files...
    tcc -impdef lib.dll [-v] [-o lib.def]

also:
- support more files with -c: tcc -c f1.c f2.c ...
- fix a bug which caused tcc f1.c f2.S to produce no asm
- allow tcc -ar @listfile too
- change prototype: _void_ tcc_set_options(...)
- apply -Wl,-whole-archive when a librariy is given
  as libxxx.a also (not just for -lxxx)