lib/armeabi.c: fix zero from/to double conversion

tccgen.c:
- allow cross-compiling 0.0L (cross-compile tcc with tcc)
tccelf.c:
- use alignment of TLS section for PT_TLS
tccpp.c:
- support long double constants on systems that do not support
  long doubles (i.e. mark them (VT_DOUBLE | VT_LONG))
tccdefs.h:
  #define __has_feature() for android
  remove _unaligned (why define a msvc extension under !_WIN32)