[RFC] Implement __builtin_bswap* for ARMv6

[Alexandre Pereira Nunes]

Hi,

It seems to me that as of ARMv6, the arm family supports the REV* 
instructions, in order to endian swap 32 and 16 bit values.

Would it be complicated to implement e.g. __builtin_bswap32 on armv6 
with inline semantics (I mean, without generating a library call)?

Thanks,

Alexandre