tests: Allow GResource external data tests to use llvm-objcopy
Relax the requirement for the test to only be compiled/run under gcc,
since a version of LLVM was released which supports
objcopy should be overrideable to be
llvm-objcopy by using a machine
file as per https://mesonbuild.com/Machine-files.html#binaries.
Suggested and tested by Grigory Vasilyev.
Signed-off-by: Philip Withnall firstname.lastname@example.org
Fixes: #2423 (closed)
Closes #2423 (closed)