Add -Wl,--build-id to default linker flags on Linux

[Colin MacLean]

-Wl,--build-id can be used to embed a unique hash into an executable or library. CCS needs this information to operate and will fall back to hashing the text segment at runtime. This linker flag moves hashing the text segments from runtime to compile time, improving performance and avoiding problems with debuggers modifying the code segment when setting breakpoints. It’s not necessary on Mac, as it’s enabled by default, but doesn’t hurt.

This linker flag is available since binutils 2.18 (released 2007) and is present on ld.bfd, ld.gold and ld.llvm, so is widely supported.

[Dan Bonachea]

Mass roll-over of open issues to next release milestone

[Dan Bonachea]

Ran into this again today trying to debug.

Raising this to Blocker due to the high impact on regular users, especially those who do not build UPC++ themselves (e.g. using an install provided by Paul or Spack).

[Dan Bonachea]

resolved in PR 497 merged at 77296a2