[llvm] [Transforms] Allow non-regex Source in SymbolRewriter in case of using ExplicitRewriteDescriptor (PR #154319)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> Currently SymbolRewriter has no tests at all. 

There's one here https://github.com/llvm/llvm-project/tree/main/llvm/test/SymbolRewriter




https://github.com/llvm/llvm-project/pull/154319