Add kotlin stdlib to javac classpath

Java modules that have .kt sources may also use kotlin stdlib types
in their .java sources.

Bug: 78245848
Test: m checkbuild
Change-Id: I064cb76b8a641ad92d648febaa400bc01549a9c5

java/java.go

@@ -928,6 +928,7 @@ func (j *Module) compile(ctx android.ModuleContext, extraSrcJars ...android.Path
 		}
 
 		// Make javac rule depend on the kotlinc rule
+		flags.classpath = append(flags.classpath, deps.kotlinStdlib...)
 		flags.classpath = append(flags.classpath, kotlinJar)
 
 		// Jar kotlin classes into the final jar after javac