Have ConvertWBp2build use Bp2buildMutatorContext

This no-op refactoring facilitates some upcoming functional changes for
"bp2build allowlist v2". The work requires that the bp2build conversion
mutator be changed from a TopDown mutator to a BottomUp mutator.
Refactoring all bp2build-related methods so that they use Bp2buildMutatorContext
makes it easier to make this functional change without touching tens of
files and multiple projects.

Bug: 285631638
Test: m bp2build
Change-Id: I3d1ef3064146e959c6f0dc315350fc9764bf2bd2
diff --git a/cc/ndk_library.go b/cc/ndk_library.go
index c13eda2..b3bb2da 100644
--- a/cc/ndk_library.go
+++ b/cc/ndk_library.go
@@ -584,7 +584,7 @@
 	return android.BazelLabelForModuleDepsWithFn(ctx, hdrLibs, addSuffix)
 }
 
-func ndkLibraryBp2build(ctx android.TopDownMutatorContext, c *Module) {
+func ndkLibraryBp2build(ctx android.Bp2buildMutatorContext, c *Module) {
 	ndk, _ := c.linker.(*stubDecorator)
 	props := bazel.BazelTargetModuleProperties{
 		Rule_class:        "cc_stub_suite",