testsuite: Add arm testcase for PR105374

testsuite: Add arm testcase for PR105374

As discussed in the PR, here is the testcase with the appropriate dg-*
directives.

Tested on arm-none-eabi with
1 -mcpu=cortex-a7/-mfloat-abi=soft/-march=armv7ve+simd
2 -mcpu=cortex-a7/-mfloat-abi=hard/-march=armv7ve+simd
3 -mthumb/-mcpu=cortex-a7/-mfloat-abi=hard/-march=armv7ve+simd
4 -mthumb/-mfloat-abi=soft/-march=armv6s-m
5 -mthumb/-mfloat-abi=soft/-march=armv7-m
6 -mthumb/-mfloat-abi=hard/-march=armv7e-m+fp
7 -mthumb/-mfloat-abi=hard/-march=armv7e-m+fp.dp
8 -mthumb/-mfloat-abi=hard/-march=armv8-m.main+fp+dsp
9 -mthumb/-mfloat-abi=hard/-march=armv8.1-m.main+mve.fp+fp.dp
10 -mthumb/-mfloat-abi=hard/-march=armv8.1-m.main+mve

The test is UNSUPPORTED with the first three ones (because of
-mcpu=cortex-a7), ignored with armv6s-m, and PASSes with all the other
ones, while it used crash without Jakub's fix (r12-8263), ie. FAIL
with options 5,6,7,8,10. The test passed without Jakub's fix with
option 9 because the problem happens only with an integer-only MVE.

2022-04-26  Christophe Lyon  <christophe.lyon@arm.com>

	gcc/testsuite/

	PR tree-optimization/105374
	* gcc.target/arm/simd/pr105374.C: New.