Make EqualModules a free function.

Bug: 377723687
Test: Unit tests and compare the ninja and mk files generated.
Change-Id: I7e00f09a15f2857f58bea70bcedc4798630a40bc
diff --git a/android/base_module_context.go b/android/base_module_context.go
index 5e05f54..d2404fd 100644
--- a/android/base_module_context.go
+++ b/android/base_module_context.go
@@ -34,8 +34,6 @@
 
 	blueprintBaseModuleContext() blueprint.BaseModuleContext
 
-	EqualModules(m1, m2 Module) bool
-
 	// OtherModuleName returns the name of another Module.  See BaseModuleContext.ModuleName for more information.
 	// It is intended for use inside the visit functions of Visit* and WalkDeps.
 	OtherModuleName(m blueprint.Module) string
@@ -271,8 +269,8 @@
 	return module
 }
 
-func (b *baseModuleContext) EqualModules(m1, m2 Module) bool {
-	return b.bp.EqualModules(getWrappedModule(m1), getWrappedModule(m2))
+func EqualModules(m1, m2 Module) bool {
+	return blueprint.EqualModules(getWrappedModule(m1), getWrappedModule(m2))
 }
 
 func (b *baseModuleContext) OtherModuleName(m blueprint.Module) string {