[mlir][NFC] Fix format specifier warning on Windows

`%ld` specifier is defined to work on values of type `long`. The parameter given to `fprintf` is of type `intptr_t` whose actual underlying integer type is unspecified. On Unix systems it happens to commonly be `long` but on 64-bit Windows it is defined as `long long`.

The cross-platform way to print a `intptr_t` is to use `PRIdPTR` which expands to the correct format specifier for `intptr_t`. This avoids any undefined behaviour and compiler warnings.

Author: zero9178

mlir/test/CAPI/llvm.c

@@ -15,6 +15,7 @@
 #include "mlir-c/Support.h"
 
 #include <assert.h>
+#include <inttypes.h>
 #include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -105,7 +106,7 @@ static int testStructTypeCreation(MlirContext ctx) {
   // CHECK: i8
   // CHECK: i32
   // CHECK: i64
-  fprintf(stderr, "num elements: %ld\n",
+  fprintf(stderr, "num elements: %" PRIdPTR "\n",
           mlirLLVMStructTypeGetNumElementTypes(literal));
   for (intptr_t i = 0; i < 3; ++i) {
     mlirTypeDump(mlirLLVMStructTypeGetElementType(literal, i));