debug_modes, re-unalign, cleanups

debug_modes, re-unalign, cleanups

tccgen.c: debug_modes
- don't waste debug function calls during normal execution.
libtcc.c:
- mem_debug: no C99 features in tcc please, for example
  ({compound expressions}): do not use.
tccgen.c: struct_layout:
- unaligned access is completely ok for most targets.
- Moreover the patch was triggering single byte mode even
  for normal aligned access (as with tcc's SymAttr)

static Sym label: don't do this

arm-gen.c:
- use some #ifdefs to explain some code
tccpp.c:
- cleanup UCN chars
libtcc.c:
- replace openbsd library search
configure:
- cleanup strip fallouts
tccgen.c:
- expr_cond(): remove an exotic optimization that eventually
  got fixed to do the contrary by a gv(RC_InT)
- pop_local_syms(): remove some args
- init_putv() : use write##le functions to avoid cross-compiler
  unaligned access
- __bt_init(): remove unused param 'mode'