Trimming mach/powerpc/ncg/table

Trimming mach/powerpc/ncg/table

Remove coercion from LABEL to REG.  The coercion never happens because
I have stopped putting LABEL on the stack.  Also remove LABEL from set
ANY_BHW.  Retain the move from LABEL to REG because pat gto uses it.

Remove li32 instruction, unused after the switch to the hi16, ha16,
lo16 syntax.

Remove COMMENT(...) lines from most moves.  In my opinion, they took
too much space, both in the table and in the assembly output.  The
stacking rules and coercions keep their COMMENT(...)  lines.

In test GPR, don't write to RSCRATCH.

Fold several coercions into a single coercion from ANY_BHW uses REG.

Use REG instead of GPR in stack patterns.  REG and GPR act the same,
because every GPR on the stack is a REG, but I want to be clear that I
expect a REG, not r0.

In code rules, sort SUM_RC before SORT_RR, so I can add SUM_RL later.

Remove rules to optimize loc loc cii loc loc cii.  If $2==$4, the
peephole optimizer can optimize it.  If $2!=$4, then the EM program is
missing a conversion from size $2 to size $4.

Remove rules to store a SEX_B with sti 1 or a SEX_H with sti 2.  These
rules would never get used, unless the EM program is missing a
conversion from size 4 to size 1 or 2.