[llvm] [LLVM][Support] check for error return from dladdr. (PR #138369)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

Btw, unrelated to this particular patch; it seems like you don't have a realname set on your github account. When merging patches via the "squash and merge" method, the patches get rewritten to use the name from the account, not the (proper) name as it was in the individual git comits - so the patches end up with just `Author: jeremyd2019 <github at jdrake.com>`.

https://github.com/llvm/llvm-project/pull/138369