[HWASAN] Fix a memory leak in realloc-test.cpp

compiler-rt/test/hwasan/TestCases/realloc-test.cpp

 // Test basic realloc functionality.
 // RUN: %clang_hwasan %s -o %t && %run %t
 // RUN: %clang_hwasan %s -DREALLOCARRAY -o %t && %run %t
 
 #include <assert.h>
 #include <sanitizer/hwasan_interface.h>
+#include <stdlib.h>
 
 #ifdef REALLOCARRAY
 extern "C" void *reallocarray(void *, size_t nmemb, size_t size);
 #define REALLOC(p, s) reallocarray(p, 1, s)
 #else
-#include <stdlib.h>
 #define REALLOC(p, s) realloc(p, s)
 #endif
 
 int main() {
   __hwasan_enable_allocator_tagging();
   char *x = (char*)REALLOC(nullptr, 4);
   x[0] = 10;
   x[1] = 20;
int main() {
   assert(x3 != x2);
   assert(x3[0] == 10 && x3[1] == 20 && x3[2] == 30 && x3[3] == 40 &&
          x3[4] == 50 && x3[5] == 60);
 
   char *x4 = (char*)REALLOC(x3, 5);
   assert(x4 != x3);
   assert(x4[0] == 10 && x4[1] == 20 && x4[2] == 30 && x4[3] == 40 &&
          x4[4] == 50);
+  free(x4);
 }