Move PassBuilder::registerParseTopLevelPipelineCallback out-of-line

For some mysterious reason it doesn't build with clang-cl when compiled
as part of the includes in clang's CodeGenAction.cpp
(crbug.com/1132292).

Author: zmodem

llvm/include/llvm/Passes/PassBuilder.h

@@ -682,9 +682,7 @@ class PassBuilder {
   /// PassManagers and populate the passed ModulePassManager.
   void registerParseTopLevelPipelineCallback(
       const std::function<bool(ModulePassManager &, ArrayRef<PipelineElement>,
-                               bool VerifyEachPass, bool DebugLogging)> &C) {
-    TopLevelPipelineParsingCallbacks.push_back(C);
-  }
+                               bool VerifyEachPass, bool DebugLogging)> &C);
 
   /// Add PGOInstrumenation passes for O0 only.
   void addPGOInstrPassesForO0(ModulePassManager &MPM, bool DebugLogging,

llvm/lib/Passes/PassBuilder.cpp

@@ -2835,3 +2835,9 @@ bool PassBuilder::isAnalysisPassName(StringRef PassName) {
 #include "PassRegistry.def"
   return false;
 }
+
+void PassBuilder::registerParseTopLevelPipelineCallback(
+    const std::function<bool(ModulePassManager &, ArrayRef<PipelineElement>,
+                             bool VerifyEachPass, bool DebugLogging)> &C) {
+  TopLevelPipelineParsingCallbacks.push_back(C);
+}