target-sparc: Introduce cpu_raise_exception_ra

Several helpers call helper_raise_exception directly, which requires
in turn that their callers have performed save_state.  The new function
allows a TCG return address to be passed in so that we can restore
PC + NPC + flags data from that.

This fixes a bug in the usage of helper_check_align, whose callers had
not been calling save_state.  It fixes another bug in which the divide
helpers used GETPC at a level other than the direct callee from TCG.

This allows the translator to avoid save_state prior to SAVE, RESTORE,
and FLUSHW instructions.

Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Richard Henderson <rth@twiddle.net>