review recent commits

review recent commits

tccpp.c:
 - revert "Preprocessor fix + new testcase"
   Fix was not a fix and nobody could understand the test.
   This reverts 6379f2ee76ac8d95c413f78b56e31a560e14ac6e
 - better fix and add new test (pp/18.c)

tccgen.c:
 - remove global variables 'in_sizeof', 'constant_p'
 - rework comma expression (gexpr())
 - merge func/data 'alias_target' codes
   (See 08c777053cb3b7f4f5d33bb0beeb82787d30ebe0)
 - move call to do_Static_assert()
 - better error: "expression expected before '%s'"
 - fix "statement after label"
    - remove unnecessary second parameter to block()
    - remove unnecessary call to decl()
    - revert changes to old C89 test file
    See 7f0a28f6ca026a0b2b50282a2168346eef668651

tccelf.c:
 - rework "...make undefined global symbol STT_NOTYPE"
   (See f44060f8fcdfa9a21bb63476cf2758d497a053b9)
 - move tccelf_add_crtbegin() from libtcc.c

tcctest:
 - unfix K&R fix (keep old look of K&R functions)

tccrun.c:
 - exit(0) returns 0

libtcc.c:
 - move #defines for -dumpmachine
 - more explicit error "file not found"
   (as opposed to error while loading file)

tccpe.c, x86_64-gen.c, i386-asm.c, tccasm.c:
 - use R_X86_64_PLT32 for functions on x86_64-win32

tccdefs.h
 - empty #defines for _Nonnull, __has_builtin(), etc.

configure:
 - Simpler "macOS .dylib ... VERSION letters."
   (See 6b967b1285704db13188895d86e7b3b34c3d2ff4)

Makefile:
 - macOS version also
 - add cross searchpaths for packages

build.yml:
 - disable codesign on macos-11 (doesn't seem to work)