Add test case to insure that implicit builtin declarations for C library functions aren't created in C++

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64513 91177308-0d34-0410-b5e6-96231b3b80d8

test/SemaCXX/no-implicit-builtin-decls.cpp

@@ -0,0 +1,7 @@
+// RUN: clang -fsyntax-only -verify %s
+
+void f() {
+  void *p = malloc(sizeof(int) * 10); // expected-error{{no matching function for call to 'malloc'}}
+}
+
+int malloc(double);