gcc: Define ElfW() if it is not defined.Better than commenting it out.Suggested-by: zrj
gcc8: Fix the fix.
gccs had ElfW() already. Comment out for now.
Update GCC80 to version 8.3
Import GCC-8 to a new vendor branch
gcc80: Add alternative variant of pthread presence checking.Port the 5f76495ba37ea12fb60cf57228cc78b83d889fb from gcc50.