valgrind: don't use FreeBSD kernel version, use libc version

Author: rhelmot

pkgs/development/tools/analysis/valgrind/default.nix

@@ -49,8 +49,7 @@ stdenv.mkDerivation rec {
   separateDebugInfo = stdenv.hostPlatform.isLinux;
 
   preConfigure = lib.optionalString stdenv.hostPlatform.isFreeBSD ''
-    substituteInPlace configure --replace '`uname -r`' \
-        ${toString stdenv.hostPlatform.parsed.kernel.version}.0-
+    substituteInPlace configure --replace-fail '`uname -r`' ${stdenv.cc.libc.version}-
   '' + lib.optionalString stdenv.hostPlatform.isDarwin (
     let OSRELEASE = ''
       $(awk -F '"' '/#define OSRELEASE/{ print $2 }' \