arm: testsuite: adjust ftest tests

arm: testsuite: adjust ftest tests

The ftest-*.c tests for Arm check certain ACLE mandated macros to ensure
they are correctly defined based on the selected architecture.  ACLE
states that the macro should be defined if the operation exists in
the hardware, but it doesn't have to exist in the current ISA because
and interworking call to the library function will still result in using
the hardware operation (both GCC and Clang agree on this).  So adjust
the tests accordingly.

Whilst cleaning this up, also remove the now redundant dg-skip-if operations
that were testing for incompatible command-line options.  That should now
be a thing of the past as the framework will clean this up more thoroughly
before running the test, or detect incompatible option combinations.

gcc/testsuite/ChangeLog:

	* gcc.target/arm/ftest-armv4t-thumb.c:  Expect __ARM_FEATURE_CLZ to be
	defined.  Remove redundant dg-skip-if rules.
	* gcc.target/arm/ftest-armv5t-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv5te-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv6-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv6k-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv6z-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv7em-thumb.c: Remove redundant dg-skip-if
	rules.  Add a require-effective-target for armv7em.
	* gcc.target/arm/ftest-armv7a-arm.c: Likewise.
	* gcc.target/arm/ftest-armv7a-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv7r-arm.c: Likewise.
	* gcc.target/arm/ftest-armv7r-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv7ve-arm.c: Likewise.
	* gcc.target/arm/ftest-armv7ve-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv8a-arm.c: Likewise.
	* gcc.target/arm/ftest-armv8a-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv4-arm.c: Remove redundant dg-skip-if rules.
	* gcc.target/arm/ftest-armv4t-arm.c: Likewise.
	* gcc.target/arm/ftest-armv5t-arm.c: Likewise.
	* gcc.target/arm/ftest-armv5te-arm.c: Likewise.
	* gcc.target/arm/ftest-armv6-arm.c: Likewise.
	* gcc.target/arm/ftest-armv6k-arm.c: Likewise.
	* gcc.target/arm/ftest-armv6m-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv6t2-arm.c: Likewise.
	* gcc.target/arm/ftest-armv6t2-thumb.c: Likewise.
	* gcc.target/arm/ftest-armv6z-arm.c: Likewise.