arm: testsuite: improve compatibility of gcc.target/arm/macro_defs*.c

arm: testsuite: improve compatibility of gcc.target/arm/macro_defs*.c

Convert these tests to use dg-add-options for increased compatibilty.
Since they also result in an empty translation unit, override the
default testsuite options.

gcc/testsuite:

	* gcc.target/arm/macro_defs0.c: Use dg-effective-target and
	dg-add-options.
	* gcc.target/arm/macro_defs1.c: Likewise.
	* gcc.target/arm/macro_defs2.c: Likewise.