Runtime lib functions

Runtime lib functions

Yesterday I felt the urge to change a few things in TinyCC.
This is the first and biggest change of all of them.

- use __aeabi_*divmod functions in ARM EABI to make binaries depend
  solely on standardized library functions

- refactor ARM floating point <-> integer conversion a bit

- rename long long->float and shift library functions to correspond to
  the names used by GCC

- compile more tokens conditionally to reduce the size of TinyCC

The intention is primarily to allow users of the ARM target to use
libgcc (which is usually available as a shared library) instead of
libtcc1 (which can't be compiled for ARM due to lack of an inline
assembler).

Changing the EABI target to use the divmod functions in theory allows
to use it without libtcc1 on any (not necessarily GCC based) ARM EABI
system.

  Daniel