testsuite/arm: Improve unsigned-float.c

testsuite/arm: Improve unsigned-float.c

The test requires an FPU, so use -march=armv7-a+fp -mfpu=auto instead
of -march=armv7-a.

We also remove dg-require-effective-target arm_fp_ok, but keep
dg-add-options arm_fp: this enables the test to pass on arm-eabi
configured with default cpu/fpu/mode.

dg-require-effective-target arm_fp_ok fails on such a configuration
for lack of FPU, since dg-options are not taken into account by
dg-require-effective-target.

Add -march=armv7-a+fp -mfpu=auto is sufficient for arm_fp options to
be acceptable.

This enables the test to pass on all the arm-eabi configurations I'm
testing, as well as arm-linux-gnueabi when forcing -march=armv5t.

2021-05-16  Christophe Lyon  <christophe.lyon@linaro.org>

	gcc/testsuite/
	* gcc.target/arm/unsigned-float.c: Remove arm_fp_ok, adjust
	dg-options.