arm: testsuite: avoid hard-float ABI incompatibility with -march

arm: testsuite: avoid hard-float ABI incompatibility with -march

A number of tests in the gcc testsuite, especially for arm-specific
targets, add various flags to control the architecture.  These run
into problems when the compiler is configured with -mfpu=auto if the
new architecture lacks an architectural feature that implies we have
floating-point instructions.

The testsuite makes this worse as it falls foul of this requirement in
the base architecture strings provided by target-supports.exp.

To fix this we add "+fp", or something equivalent to this, to all the
base architecture specifications.  The feature will be ignored if the
float ABI is set to soft.

gcc/testsuite:

	* lib/target-supports.exp (check_effective_target_arm_arch_FUNC_ok):
	Add base FPU specifications to all architectures that can support
	one.