testsuite: arm: Use check-function-bodies in fp16-aapcs-* tests

Converted the tests to use check-function-bodies in order to ensure that
the sequence is correct.

gcc/testsuite/ChangeLog:

	* gcc.target/arm/fp16-aapcs-1.c: Use check-function-bodies.
	* gcc.target/arm/fp16-aapcs-2.c: Likewise.
	* gcc.target/arm/fp16-aapcs-3.c: Likewise.
	* gcc.target/arm/fp16-aapcs-4.c: Likewise.

Signed-off-by: Torbjörn SVENSSON <torbjorn.svensson@foss.st.com>