Specify architecture for SPARC gas tests

Specify architecture for SPARC gas tests

A couple of SPARC gas tests FAIL on Solaris/SPARC (both
sparc-sun-solaris2.11 and sparcv9-sun-solaris2.11):

FAIL: sparc PAUSE
FAIL: sparc CBCOND
FAIL: sparc CFR
FAIL: sparc CRYPTO
FAIL: sparc HPC+VIS3
FAIL: sparc IMA
FAIL: sparc OSA2015 %mwait asr and MWAIT instruction
FAIL: sparc OSA2015 %mcdper asr
FAIL: sparc SPARC5 and VIS4.0
FAIL: OSA2015 crypto instructions
FAIL: SPARC6
FAIL: FPCMPSHL OSA2017 instructions
FAIL: OSA2017 ONADD/ONSUB/ONMUL/ONDIV instructions.
FAIL: OSA2017 RLE instructions
FAIL: sparc64 rdasr
FAIL: sparc64 rdpr
FAIL: sparc64 rdhpr
FAIL: sparc64 wrasr
FAIL: sparc64 wrpr

It turns out there's a common pattern here: failures happen for all
tests that use SPARC ISA extensions beyond sparcv9, e.g. for the sparc
PAUSE test:

regexp_diff match failure
regexp "^   0:  b7 80 40 02     wr  %g1, %g2, %pause$"
line   "   0:   b7 80 40 02     wr  %g1, %g2, %asr27"
[...]
regexp_diff match failure
regexp "^   8:  b7 80 20 08     pause  8$"
line   "   8:   b7 80 20 08     wr  8, %asr27"
[...]

The fix is easy, actually: just as the tests specify the ISA extension
to use as a gas flag, the same needs to be done for objdump.  For the
test above, which has -Av9v, this means passing -msparc:v9v to objdump.
Doing so makes all but two (unrelated; to be reported separately)
failures go away.

This doesn't happen on Linux/SPARC, where gas emits GNU object attributes
matching the hardcare capabilities used.  Since gas doesn't yet implement
Solaris-style object capabilites, the explicit -march is needed, but only
passed on Solaris.

Tested on both sparc-sun-solaris2.11 and sparcv9-sun-solaris2.11.

	* testsuite/gas/sparc/sparc.exp (set_tests_arch): New proc.
	Prefix v9c, v9d, v9v, v9m, v9m8 tests with corresponding
	set_tests_arch.