[NFC] Update the test compiler to use clangxx.

This ensures that the c++ test gets the right CXXFLAGS if required.

GitOrigin-RevId: 9305e3b6d7e721ba5d09d971df4f65bf892f58ad
diff --git a/test/memprof/TestCases/interface_test.cpp b/test/memprof/TestCases/interface_test.cpp
index 451ab57..aa3b24f 100644
--- a/test/memprof/TestCases/interface_test.cpp
+++ b/test/memprof/TestCases/interface_test.cpp
@@ -1,8 +1,8 @@
 // Check that user may include MemProf interface header.
 // Also check that interfaces declared in the sanitizer's allocator_interface
 // are defined for MemProf.
-// RUN: %clang_memprof %s -o %t -DMEMPROF && %run %t
-// RUN: %clang_memprof -x c %s -o %t -DMEMPROF && %run %t
+// RUN: %clangxx_memprof %s -o %t -DMEMPROF && %run %t
+// RUN: %clangxx_memprof -x c %s -o %t -DMEMPROF && %run %t
 // RUN: %clang %s -pie -o %t && %run %t
 // RUN: %clang -x c %s -pie -o %t && %run %t
 #include <sanitizer/allocator_interface.h>