[ARM] Fix test fail with conflicting -mfloat-abi

[ARM] Fix test fail with conflicting -mfloat-abi

This patch fixes my earlier test case that fails for arm-none-eabi
with explicit user option for -mfloat-abi which conflict with
the test case options. I have added a guard to skip the test
on those cases.

ChangeLog entries:

*** gcc/testsuite/ChangeLog ***

2018-01-22  Sudakshina Das  <sudi.das@arm.com>

	* gcc.c-torture/compile/pr82096.c: Add dg-skip-if and
	dg-require-effective-target directives.

From-SVN: r256941