Add legacy-performance-test-hostdex target

This is needed for some internal targets that currently depend
directly on the source files and which break when the source
file is moved.

Bug: 30188076
Test: make legacy-performance-test-hostdex
Change-Id: I653325605204c1f272bd5f669e2297eedeaf7d61
diff --git a/legacy-test/Android.mk b/legacy-test/Android.mk
index fe5d8ca..0011002 100644
--- a/legacy-test/Android.mk
+++ b/legacy-test/Android.mk
@@ -27,3 +27,15 @@
 LOCAL_MODULE := legacy-test
 
 include $(BUILD_JAVA_LIBRARY)
+
+ifeq ($(HOST_OS),linux)
+# Build the legacy-performance-test-hostdex library
+# =================================================
+# This contains the android.test.PerformanceTestCase class only
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := ../core/java/android/test/PerformanceTestCase.java
+LOCAL_MODULE := legacy-performance-test-hostdex
+
+include $(BUILD_HOST_DALVIK_JAVA_LIBRARY)
+endif  # HOST_OS == linux