Revert "Prevent config.h from being clobbered"

This reverts commit 28bba8c44f.

src/libstore/globals.hh

@@ -50,6 +50,9 @@ struct Settings {
     /* The directory where the main programs are stored. */
     Path nixBinDir;
 
+    /* File name of the socket the daemon listens to.  */
+    Path nixDaemonSocketFile;
+
     /* Whether to keep temporary directories of failed builds. */
     bool keepFailed;