Fix a few mangled test files

These were mangled in the process of pulling them out of the msvc fork

- null_deref_multiple_dlls.cpp -- extern "C" { got removed
- throw_invoke_test.cpp -- #include "defines.h" is needed for
  ATTRIBUTE_NOINLINE, this test is unsupported on msvc so this was not
  caught

Author: barcharcraz

compiler-rt/test/asan/TestCases/Windows/null_deref_multiple_dlls.cpp

@@ -28,6 +28,7 @@ extern "C" {
 __declspec(dllexport) void foo1() {}
 }
 #elif defined(DLL2)
+extern "C" {
 ATTRIBUTE_NOINLINE
 static void NullDeref(int *ptr) {
   // CHECK: ERROR: AddressSanitizer: access-violation on unknown address

compiler-rt/test/asan/TestCases/throw_invoke_test.cpp

@@ -4,6 +4,8 @@
 // Investigate why it fails with NDK 21.
 // UNSUPPORTED: android, MSVC
 
+
+#include "defines.h"
 #include <stdio.h>
 static volatile int zero = 0;
 inline void pretend_to_do_something(void *x) {