Add Big-endian PowerPC code coverage measurement #1679
Description
Right now neither 32-bit nor 64-bit PowerPC code coverage is being measured in CI because neither target supports the profiler builtins.
powerpc64le-unknown-linux-gnu does support the profiler builtins.
Also @uweigand added profiler builtins to the s390x-unknown-linux-gnu in rust-lang/rust#104304, so big-endian support is already there.