Add back test that was in the wrong directory

Author: Sirraide

clang/test/Sema/missing-dllimport.c

@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -triple i686-pc-win32 -fms-extensions -verify %s
+
+// Do not report that 'foo()' is redeclared without dllimport attribute.
+// specified.
+
+// expected-no-diagnostics
+__declspec(dllimport) int __cdecl foo(void);
+inline int __cdecl foo() { return 0; }