[clang] Fix Dependency Scanning Test Failures Caused by deed6e90081889e851be7b6cfcdc6a04bbd142e5

[qiongsiwu]

It seems that deed6e9 accidentally added DepCollectorPPCallbacks twice, which led to the following 5 test case failures.

Clang :: Frontend/dependency-gen-phony.c
Clang :: Modules/dependency-skip-unused-modulemaps.m
Clang-Unit :: Tooling/./ToolingTests/DependencyScanner/ScanDepsReuseFilemanager
Clang-Unit :: Tooling/./ToolingTests/DependencyScanner/ScanDepsReuseFilemanagerHasInclude
Clang-Unit :: Tooling/./ToolingTests/DependencyScanner/ScanDepsReuseFilemanagerSkippedFile

This PR removes the duplicate and fixes the failing tests.

rdar://142333288

[qiongsiwu]

@swift-ci please test

[qiongsiwu]

@swift-ci Please test LLVM

[cyndyishida]

It looks like there are still some clangd unit tests failing, are those unrelated?

  Clangd Unit Tests :: ./ClangdTests/20/40
  Clangd Unit Tests :: ./ClangdTests/21/40
  Clangd Unit Tests :: ./ClangdTests/25/40

[qiongsiwu]

Looking into the extra clangd failures. I cannot reproduce them locally yet, and it seems that the Linux and macOS CI runs are showing different clangd failures. The failures may be intermittent.

Linux (https://ci.swift.org/job/pr-apple-llvm-project-llvm-linux/482/console)

  Clangd Unit Tests :: ./ClangdTests/20/40
  Clangd Unit Tests :: ./ClangdTests/21/40
  Clangd Unit Tests :: ./ClangdTests/25/40

macOS (https://ci.swift.org/job/pr-apple-llvm-project-llvm-macos/478/console)

  Clangd Unit Tests :: ./ClangdTests/0/20
  Clangd Unit Tests :: ./ClangdTests/1/20
  Clangd Unit Tests :: ./ClangdTests/5/20

[qiongsiwu]

It seems that the clangd failures already exist before. For example #9803 's tests hit them as well. This PR does not really change their state. I cannot reproduce these failures locally on macOS.

[benlangmuir]

Note: this started failing again. It looks like the same merge issue was reintroduced in 44aa7a0 which merged a revert of ca2ab74. Fixing in #9851