Convert libbinderwrapper_test_support to be a static library

Some unittests require libbinderwrapper_test_support.so and fail
because it isn't on userdebug images.

Bug: 30631078, 35804180
Test: `make dist`

(cherry picked from commit 6515f36e43082ea105115de7e34d9cd09c77220a)

Change-Id: I4d8878de8963d0cbd29d6aca4b233ba674121688
diff --git a/libbinderwrapper/Android.mk b/libbinderwrapper/Android.mk
index b38d262..c768373 100644
--- a/libbinderwrapper/Android.mk
+++ b/libbinderwrapper/Android.mk
@@ -41,7 +41,7 @@
 
 include $(BUILD_SHARED_LIBRARY)
 
-# libbinderwrapper_test_support shared library
+# libbinderwrapper_test_support static library
 # ========================================================
 
 include $(CLEAR_VARS)
@@ -59,4 +59,4 @@
   binder_test_base.cc \
   stub_binder_wrapper.cc \
 
-include $(BUILD_SHARED_LIBRARY)
+include $(BUILD_STATIC_LIBRARY)