racket: use proper uname, allow for unix sockets

Racket checks the current platform via uname, then disallows
unix domain socket usage based on the result. Previously, it could not
successfully call uname at all, so it fell back to denying UDS.

pkgs/development/interpreters/racket/default.nix

@@ -58,7 +58,9 @@ stdenv.mkDerivation rec {
 
   preConfigure = ''
     unset AR
-    substituteInPlace src/configure --replace /usr/bin/uname ${coreutils}/bin/uname
+    for f in src/configure src/racket/src/string.c; do
+      substituteInPlace "$f" --replace /usr/bin/uname ${coreutils}/bin/uname
+    done
     mkdir src/build
     cd src/build
   '';