Remove -Wno-error=unused-function

Test: pass
Change-Id: I368ba474e020f21c3bdfcb0f7f8a58e79bc089da
diff --git a/test/main.cpp b/test/main.cpp
index 495b35c..507e0d1 100644
--- a/test/main.cpp
+++ b/test/main.cpp
@@ -39,11 +39,13 @@
 extern const XmlConverter<HalManifest> &gHalManifestConverter;
 extern const XmlConverter<CompatibilityMatrix> &gCompatibilityMatrixConverter;
 
+#ifdef LIBVINTF_HOST
 static bool Contains(const std::string& str, const std::string& sub) {
     return str.find(sub) != std::string::npos;
 }
 #define EXPECT_CONTAINS(str, sub) \
     EXPECT_TRUE(Contains((str), (sub))) << "Cannot find \"" << (sub) << "\" in \"" << (str) << "\""
+#endif
 
 struct LibVintfTest : public ::testing::Test {
 public: