(SPARC_{V9,ARCH64}): Default value is 0.

(*): Replace SPARCV9 with SPARC_{V9,ARCH64}.
(MASK_CPUS): Define.
({MASK,TARGET}_ENV32): Delete.
({MASK,TARGET}_ARCH64,TARGET_ARCH32): Define.
(TARGET_SWITCHES): Reset cpu flags first for each variant.
(CONDITIONAL_REGISTER_USAGE): If 32 bit v9 system, unfix g1-g4,
fix g5, and make %f48-%f80 call used.

From-SVN: r11100