glibc: put back the nscd check, by $out instead of date

I don't know why they feel they need to check the compatibility by build date,
so I would keep check against $out, which is a better nix equivalent.

Also, expression refactoring (put comments out of hash-changing bash).

pkgs/development/libraries/glibc/2.19/common.nix

@@ -64,21 +64,24 @@ stdenv.mkDerivation ({
 
       /* Remove references to the compilation date.  */
       ./glibc-remove-date-from-compilation-banner.patch
-
-      /* Remove the date and time from nscd.  It is used as a protocol
-         compatibility check, but we assume nix takes care of that for
-         us. */
-      ./glibc-remove-datetime-from-nscd.patch
     ];
 
-  postPatch = ''
+  postPatch =
     # Needed for glibc to build with the gnumake 3.82
     # http://comments.gmane.org/gmane.linux.lfs.support/31227
+    ''
       sed -i 's/ot \$/ot:\n\ttouch $@\n$/' manual/Makefile
-
+    ''
     # nscd needs libgcc, and we don't want it dynamically linked
     # because we don't want it to depend on bootstrap-tools libs.
+    + ''
       echo "LDFLAGS-nscd += -static-libgcc" >> nscd/Makefile
+    ''
+    # Replace the date and time in nscd by $out.
+    #  It is used as a protocol compatibility check.
+    + ''
+      cat ${./glibc-remove-datetime-from-nscd.patch} \
+        | sed "s,@out@,$out," | patch -p1
     '';
 
   configureFlags =

pkgs/development/libraries/glibc/2.19/glibc-remove-datetime-from-nscd.patch

@@ -1,11 +1,11 @@
---- a/nscd/nscd_stat.c	2014-04-08 20:35:24.253715420 +0200
+--- a/nscd/nscd_stat.c
-+++ b/nscd/nscd_stat.c	2014-04-08 20:38:32.526634400 +0200
++++ b/nscd/nscd_stat.c
 @@ -37,7 +37,7 @@
  
  
  /* We use this to make sure the receiver is the same.  */
 -static const char compilation[21] = __DATE__ " " __TIME__;
-+static const char compilation[21] = "Thu  1 1970 00:00:01"; /* __DATE__ " " __TIME__; */
++static const char compilation[21] = "@out@";
  
  /* Statistic data for one database.  */
  struct dbstat