Support dex_import on platform_bootclasspath

Maintain compatibility with previous behavior by ignoring dex_import
during hidden API processing.

Bug: 179354495
Test: m nothing
Change-Id: I976b02129bf981b7b61dce233567d6f89e04f92d

java/platform_bootclasspath.go

@@ -321,6 +321,8 @@ func (b *platformBootclasspathModule) generateHiddenAPIBuildActions(ctx android.
 			}
 
 			hiddenAPISupportingModules = append(hiddenAPISupportingModules, hiddenAPISupportingModule)
+		} else if _, ok := module.(*DexImport); ok {
+			// Ignore this for the purposes of hidden API processing
 		} else {
 			ctx.ModuleErrorf("module %s of type %s does not support hidden API processing", module, ctx.OtherModuleType(module))
 		}