[clang][PATCH][nfc] Refactor TargetInfo::adjust to pass DiagnosticsEn…

[edymtt]

…gine to allow diagnostics on target-unsupported options

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D104729

This code is necessary for building the next swift compiler on the next llvm.

(cherry picked from commit aaba371)

[edymtt]

@swift-ci please test

[edymtt]

@swift-ci please test Linux

[edymtt]

Linux testing is hitting almost the same failures as #3074 (except LLVM :: CodeGen/AArch64/arm64e-ptrauth-invoke.ll)

15:36:34 1 warning(s) in tests
15:36:34 ********************
15:36:34 Failed Tests (17):
15:36:34   Clang :: Refactor/Extract/captured-variable-types.m
15:36:34   Clang :: Refactor/Extract/extract-objc-property.m
15:36:34   Clang :: Refactor/Extract/return-block.m
15:36:34   Clangd :: background-index.test
15:36:34   Clangd :: check-fail.test
15:36:34   Clangd :: check-lines.test
15:36:34   Clangd :: check.test
15:36:34   Clangd :: compile-commands-path-in-initialize.test
15:36:34   Clangd :: path-mappings.test
15:36:34   Clangd :: system-include-extractor.test
15:36:34   Clangd :: target_info.test
15:36:34   Clangd Unit Tests :: ./ClangdTests/DirectoryBasedGlobalCompilationDatabaseCacheTest.Cacheable
15:36:34   Clangd Unit Tests :: ./ClangdTests/GlobalCompilationDatabaseTest.BuildDir
15:36:34   Clangd Unit Tests :: ./ClangdTests/GlobalCompilationDatabaseTest.CompileFlagsDirectory
15:36:34   Clangd Unit Tests :: ./ClangdTests/GlobalCompilationDatabaseTest.Config
15:36:34   Clangd Unit Tests :: ./ClangdTests/GlobalCompilationDatabaseTest.DiscoveryWithNestedCDBs
15:36:34   Clangd Unit Tests :: ./ClangdTests/LSPTest.CDBConfigIntegration

Merging to allow Swift rebranch to build.