tested on win32/64 to pass the tests when enabled
- libtcc.c :
let tcc define __leading_underscore if enabled
tcc_add_symbol() : add _ automatically
- tccelf.c : remove tcc_get_symbol_err(), find_c_sym()
currently symbol length is limited to 256 in several
places, so we can use a fixed local buffer for now as well.
- win32/lib/crtinit.c : new file for init/fini
- lib/*.S, tests7* : use __leading_underscore
- bt-log.c: this file wont work relibaly if compiled with gcc
via some heavy-handed hackery in the ASM symbol handling in case
C symbols get a leading underscore (but ASM symbols do not).
But this is now like clang and GCC on Darwin work: asm symbols are
undecorated, C symbols get a _ prepended, so to connect both some
trickery is involved for the ASM symbols that don't have a _ prepended.
They must be included in the C symbol table (because that's what we use
to lookup also ASM labels), but they also must not disturb the normal
C symbol (which don't have the _ prepended), so they need some mangling.
A bit unsatisfying, but well. So, add asm-c-connect-test to the working
ones for Darwin as well.
