[clang] [clang][Modules] Restore module search on the MODULE_MAP_FILE relocation check (PR #219521)

[Qiongsi Wu via cfe-commits]

qiongsiwu wrote:

@cyndyishida I noticed this gap when I was looking at https://github.com/llvm/llvm-project/pull/219107. Was this an intentional change? Changing the flag to `true` inside  `getModuleForRelocationChecks` fixes the regression, but I'd love to hear if you have other ideas. 

https://github.com/llvm/llvm-project/pull/219521