[NFC] Fix comments in PassBuilder functions (#89513)

The original comments mention `addPreLinkLTODefaultPipeline`, but I
could not find any functions with this name, even in
https://reviews.llvm.org/D33540
(8b3be4e) where this comment was added.
I assume they meant to refer to `buildThinLTOPreLinkDefaultPipeline` and
`buildLTOPreLinkDefaultPipeline` and so this patch uses them.

llvm/include/llvm/Passes/PassBuilder.h

@@ -264,12 +264,12 @@ class PassBuilder {
   /// the LTO run.
   ModulePassManager buildThinLTOPreLinkDefaultPipeline(OptimizationLevel Level);
 
-  /// Build an ThinLTO default optimization pipeline to a pass manager.
+  /// Build a ThinLTO default optimization pipeline to a pass manager.
   ///
   /// This provides a good default optimization pipeline for link-time
   /// optimization and code generation. It is particularly tuned to fit well
   /// when IR coming into the LTO phase was first run through \c
-  /// addPreLinkLTODefaultPipeline, and the two coordinate closely.
+  /// buildThinLTOPreLinkDefaultPipeline, and the two coordinate closely.
   ModulePassManager
   buildThinLTODefaultPipeline(OptimizationLevel Level,
                               const ModuleSummaryIndex *ImportSummary);
@@ -288,7 +288,7 @@ class PassBuilder {
   /// This provides a good default optimization pipeline for link-time
   /// optimization and code generation. It is particularly tuned to fit well
   /// when IR coming into the LTO phase was first run through \c
-  /// addPreLinkLTODefaultPipeline, and the two coordinate closely.
+  /// buildLTOPreLinkDefaultPipeline, and the two coordinate closely.
   ModulePassManager buildLTODefaultPipeline(OptimizationLevel Level,
                                             ModuleSummaryIndex *ExportSummary);