Implement LOCAL_TARGET_REQUIRED_MODULES

to allow a host module to specify LOCAL_TARGET_REQUIRED_MODULES
to indicate that the device module should be built.

Bug: b/64580523
Test: add "LOCAL_TARGET_REQUIRED_MODULES := \
      CtsDeviceOsTestApp CtsHostProcfsTestApp" to \
      cts/hostsidetests/os/Android.mk, run \
      `m -j CtsOsHostSideTestCases`, check \
      that CtsDeviceOsTestApp.apk was built

Change-Id: I1457a51f7cd922c059aa62955d8693b1a7539fd9
diff --git a/core/base_rules.mk b/core/base_rules.mk
index 07d1cd9..57ac23c 100644
--- a/core/base_rules.mk
+++ b/core/base_rules.mk
@@ -579,6 +579,9 @@
 ALL_MODULES.$(my_register_name).EXPLICITLY_REQUIRED := \
     $(strip $(ALL_MODULES.$(my_register_name).EXPLICITLY_REQUIRED)\
         $(my_required_modules))
+ALL_MODULES.$(my_register_name).TARGET_REQUIRED := \
+    $(strip $(ALL_MODULES.$(my_register_name).TARGET_REQUIRED)\
+        $(LOCAL_TARGET_REQUIRED_MODULES))
 ALL_MODULES.$(my_register_name).EVENT_LOG_TAGS := \
     $(ALL_MODULES.$(my_register_name).EVENT_LOG_TAGS) $(event_log_tags)
 ALL_MODULES.$(my_register_name).MAKEFILE := \