Fixed nfc-extras build files

The com.android.nfc_extras target was including the test class.
The nfc-extras/tests/Android.mk file was not being included so
was not being built by continuous build and could not be built
using make NfcExtrasTests.

Bug: 38487370
Bug: 30188076
Test: make checkbuild
Change-Id: I17f6723b899f26de329a2e74177bd02ba864b7b2

nfc-extras/Android.mk

@@ -4,10 +4,10 @@ include $(CLEAR_VARS)
 
 LOCAL_MODULE_TAGS := optional
 
-LOCAL_SRC_FILES := $(call all-subdir-java-files)
-
-LOCAL_STATIC_JAVA_LIBRARIES := junit legacy-android-test
+LOCAL_SRC_FILES := $(call all-java-files-under, java)
 
 LOCAL_MODULE:= com.android.nfc_extras
 
 include $(BUILD_JAVA_LIBRARY)
+
+include $(call all-makefiles-under,$(LOCAL_PATH))

nfc-extras/tests/Android.mk

@@ -22,6 +22,8 @@ LOCAL_JAVA_LIBRARIES := \
     android.test.runner \
     com.android.nfc_extras
 
+LOCAL_STATIC_JAVA_LIBRARIES := junit legacy-android-test
+
 # Include all test java files.
 LOCAL_SRC_FILES := $(call all-java-files-under, src)