NativeHelper: Avoid returning local stack string

Refactor JniInvocation::GetLibrary to not return a stack-allocated
string. Instead, provide a char buffer.

Bug: 16404669

(cherry picked from commit 88b84ec200091bdf5754b435ef55dfcd30078a67)

Change-Id: Id5c1857eb0fdd413b87f839d0c57168d587b5c11
diff --git a/tests/Android.mk b/tests/Android.mk
index c357b24..b40bdf8 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -8,14 +8,7 @@
 LOCAL_MODULE := JniInvocation_test
 LOCAL_CLANG := true
 LOCAL_SRC_FILES := JniInvocation_test.cpp
-LOCAL_SHARED_LIBRARIES := \
-    libnativehelper
-
-include external/libcxx/libcxx.mk
-
-LOCAL_MULTILIB := both
-LOCAL_MODULE_STEM_32 := $(LOCAL_MODULE)32
-LOCAL_MODULE_STEM_64 := $(LOCAL_MODULE)64
+LOCAL_SHARED_LIBRARIES := libnativehelper
 include $(BUILD_NATIVE_TEST)
 
 # Host unit test.
@@ -24,12 +17,5 @@
 LOCAL_MODULE := JniInvocation_test
 LOCAL_CLANG := true
 LOCAL_SRC_FILES := JniInvocation_test.cpp
-LOCAL_SHARED_LIBRARIES := \
-    libnativehelper
-
-include external/libcxx/libcxx.mk
-
-LOCAL_MULTILIB := both
-LOCAL_MODULE_STEM_32 := $(LOCAL_MODULE)32
-LOCAL_MODULE_STEM_64 := $(LOCAL_MODULE)64
+LOCAL_SHARED_LIBRARIES := libnativehelper
 include $(BUILD_HOST_NATIVE_TEST)