Clarify HAL SPARC64 support situation in sparcv9a-mont.pl.

# implementations from compatibility matrix. But the rest, whole Sun

# UltraSPARC family and brand new Fujitsu's SPARC64 V, all support

# VIS extension instructions used in this module. This is considered

# good enough to recommend HAL SPARC64 users [if any] to simply fall

# down to no-asm configuration.

# good enough to not care about HAL SPARC64 users [if any] who have

# integer-only pure SPARCv9 module to "fall down" to.

# USI&II cores currently exhibit uniform 2x improvement [over pre-

# bn_mul_mont codebase] for all key lengths and benchmarks. On USIII

# is pipelined, which in turn *might* be impossible to match... On

# additional note, SPARC64 V implements FP Multiply-Add instruction,

# which is perfectly usable in this context... In other words, as far

# as HAL/Fujitsu SPARC64 family goes, talk to the author:-)

# as Fujitsu SPARC64 V goes, talk to the author:-)

# The implementation implies following "non-natural" limitations on

# input arguments: