target-sparc: Simplify ICC generation.

Use int32 types instead of target_ulong when computing ICC.  This
simplifies the generated code for 32-bit host and 64-bit guest.
Use the same simplified expressions for ICC as were already used
for XCC in carry flag generation.

Simplify the ADD carry generation to not consider a possible carry-in.
Use the more complex carry computation for ADDX only.  Use the same
carry algorithm for the XCC result of ADDX.  Similarly for SUB/SUBX.

Use the ADD carry generation functions for TADD/TADDTV.  Similarly
for SUB and TSUB/TSUBTV.

Tidy the code with respect to CODING_STYLE.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>