libsysprof-capture: Use unlink() rather than g_unlink()

They’re equivalent.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Helps: #40

src/libsysprof-capture/sysprof-capture-writer.c

@@ -988,7 +988,7 @@ handle_errno:
   if (fd != -1)
     {
       close (fd);
-      g_unlink (filename);
+      unlink (filename);
     }
 
   return false;