[Lightning] sse instructions and gcc warnings

[Paulo César Pereira de Andrade]

  Hi,

  I did some more extra work in the lightning jit code generation
in my language
http://code.google.com/p/exl/source/browse/trunk/lib/elightning.c

  It is still basically using lightning only to glue calls to C
functions, but I added some extra code for statically typed objects
yesterday and today...

  But about @subject:
elightning.c:1664: warning: left-hand operand of comma expression has no
effect
elightning.c:1664: warning: value computed is not used

any code using the float registers shows those. There are some others
on x86_64 that cannot be masked, due to mixing int32 and void*.

  A strange one is:
elightning.c:1616: warning: implicit declaration of function ‘jit_replace’
elightning.c:1616: warning: nested extern declaration of ‘jit_replace’

that probably is harmless, as it links and works.

  Also about @subject, I needed to add a global function to check
if a double is zero, because apparently the i387 goes nonsense if
a function using vector instructions was called. Currently direct
assembly is not used, but there is math to vectors with
__attribute__((vector_size(16))),
what causes sse vector instructions to be used.

Thanks,
Paulo