llvm-project

e7698a13 - Re-apply "[ORC][JITLink] Treat common symbols as weak definitions." with fixes.

Re-apply "[ORC][JITLink] Treat common symbols as weak definitions." with fixes. This reapplies 785d376d123, which was reverted in c49837f5f68 due to bot failures. The fix was to relax some asserts to allow common symbols to be resolved with either common or weak flags, rather than requiring one or the other.