[clang] Fix false match on nullPointerConstant for array indices (PR #201893)

[Aaron Ballman via cfe-commits]

================
@@ -4049,6 +4049,7 @@ TEST_P(ASTMatchersTest, NullPointerConstant) {
   EXPECT_TRUE(matches("char *cp = (char *)0;", expr(nullPointerConstant())));
   EXPECT_TRUE(matches("int *ip = 0;", expr(nullPointerConstant())));
   EXPECT_FALSE(matches("int i = 0;", expr(nullPointerConstant())));
+  EXPECT_FALSE(matches("int *p[1]; (void)p[0];", expr(nullPointerConstant())));
----------------
AaronBallman wrote:

Can you add an additional test case:
```
EXPECT_TRUE(matches("int index; (void)index[(int*)0];", expr(nullPointerConstant())));
```

https://github.com/llvm/llvm-project/pull/201893