testsuite: Common up the ifdef blocks for compiler-specific macros
testsuite: Common up the ifdef blocks for compiler-specific macros

plicease/libffi,bgarrels/libffi,rth7680/libffi,Pan7/libffi,bgarrels/libffi,plicease/libffi,Pan7/libffi,Distrotech/libffi,johne53/MB3Libffi,plicease/libffi,biosbits/libffi,Distrotech/libffi,johne53/MB3Libffi,nmav/libffi,Distrotech/libffi,Pan7/libffi,Pan7/libffi,plicease/libffi,johne53/MB3Libffi,joshtriplett/libffi,joshtriplett/libffi,johne53/MB3Libffi,rth7680/libffi,biosbits/libffi,nmav/libffi,nmav/libffi,johne53/MB3Libffi,biosbits/libffi,nmav/libffi,s1341/libffi,joshtriplett/libffi,joshtriplett/libffi,biosbits/libffi,Distrotech/libffi,s1341/libffi,s1341/libffi,s1341/libffi,rth7680/libffi,bgarrels/libffi,rth7680/libffi,bgarrels/libffi