src: fix compiler warning in src/heap_utils.cc

Fixes: nodejs#43577
Signed-off-by: Darshan Sen <raisinten@gmail.com>

PR-URL: nodejs#43579
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

src/heap_utils.cc

@@ -245,7 +245,7 @@ class FileOutputStream : public v8::OutputStream {
         status_ = num_bytes_written;
         return kAbort;
       }
-      DCHECK_LE(num_bytes_written, buf.len);
+      DCHECK_LE(static_cast<size_t>(num_bytes_written), buf.len);
       offset += num_bytes_written;
     }
     DCHECK_EQ(offset, size);