[libc] Fix test not including 'free'

Summary:
A previous change removed a transient inclusion of `stdlib.h` from the
`string_utils.h` file which this test depended on. Include it directly
here.

diff --git a/libc/test/integration/src/unistd/getcwd_test.cpp b/libc/test/integration/src/unistd/getcwd_test.cpp
index 80b45ef..5e52155 100644 (file)
--- a/libc/test/integration/src/unistd/getcwd_test.cpp
+++ b/libc/test/integration/src/unistd/getcwd_test.cpp
@@ -13,6 +13,7 @@
 #include "utils/IntegrationTest/test.h"
 
 #include <errno.h>
+#include <stdlib.h> // For malloc and free
 
 using __llvm_libc::cpp::string_view;