[clang] [Clang] fix crash in codegen caused by deferred asm diagnostics under -fopenmp (PR #147163)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> If a function has a deferred diagnostic, it should prevent codegen of that function, yes.

Deferred errors only, though, right? Do we know if there are any cases where we defer the diagnostic because we may later decide it's *not* an error and thus codegen would be fine? (I'm less familiar with deferred diagnostics, so I may be asking something silly.)

https://github.com/llvm/llvm-project/pull/147163