gcc: Fix warnings for gcc 4.7 and clang 3.1

This patch fixes two warnings, one related to a narrowing conversion
(int to MachInst), and one due to the cast operator for arguments and
a mismatch in const-ness (const void* and void*).

SPARC: Clean up some historical style issues.

SPARC: Make the spill and fill handlers use the correct ASI, and let No_Fault ASI accesses work.

Forgot to commit this new file last earlier.