On Darwin/mach-o, llvm-size (and size) will output something like
While on other platforms (e.g. GNU) you'll get
codesize.py was basically pushing that platform-specific info along in its size
So, depending on the platform, we'd get
Tools downstream from the test suite then would have to handle whatever output
the target-specific tools would produce.
Instead of doing that, let's just output something like
So all downstream consumers can just handle one single format.
This is in tandem with D146257 in LNT.