cmake: When there is no stdenv.glibc, still fix search paths.

Apply all of the fixups from preConfigure as well!

For testing purposes I added the following assert:

assert (stdenv ? glibc) -> (stdenv.glibc == stdenv.cc.libc);

To ensure behavior in the case there is a 'stdenv.glibc' (linux-only?)
wasn't changed, which passes in the configurations I could think of.

Not including that since it seems like a bad requirement moving forward.

pkgs/development/tools/build-managers/cmake/2.8.nix

@@ -5,6 +5,8 @@
 with stdenv.lib;
 
 assert wantPS -> (ps != null);
+assert stdenv ? cc;
+assert stdenv.cc ? libc;
 
 let
   os = stdenv.lib.optionalString;
@@ -31,9 +33,8 @@ stdenv.mkDerivation rec {
       url = "http://www.cmake.org/Bug/file_download.php?file_id=4660&type=bug";
       sha256 = "136z63ff83hnwd247cq4m8m8164pklzyl5i2csf5h6wd8p01pdkj";
     })] ++
-    # Don't search in non-Nix locations such as /usr, but do search in
-    # Nixpkgs' Glibc.
-    optional (stdenv ? glibc) ./search-path.patch ++
+    # Don't search in non-Nix locations such as /usr, but do search in our libc.
+    [ ./search-path.patch ] ++
     optional (stdenv ? cross) (fetchurl {
       name = "fix-darwin-cross-compile.patch";
       url = "http://public.kitware.com/Bug/file_download.php?"
@@ -50,22 +51,24 @@ stdenv.mkDerivation rec {
   CMAKE_PREFIX_PATH = concatStringsSep ":"
     (concatMap (p: [ (p.dev or p) (p.out or p) ]) buildInputs);
 
-  configureFlags =
-    "--docdir=/share/doc/${name} --mandir=/share/man --system-libs --no-system-libarchive"
-    + stdenv.lib.optionalString useQt4 " --qt-gui";
+  configureFlags = [
+    "--docdir=/share/doc/${name}"
+    "--mandir=/share/man"
+    "--system-libs"
+    "--no-system-libarchive"
+   ] ++ stdenv.lib.optional useQt4 "--qt-gui";
 
   setupHook = ./setup-hook.sh;
 
   dontUseCmakeConfigure = true;
 
-  preConfigure = with stdenv; optionalString (stdenv ? glibc)
-    ''
+  preConfigure = with stdenv; ''
       source $setupHook
       fixCmakeFiles .
       substituteInPlace Modules/Platform/UnixPaths.cmake \
-        --subst-var-by glibc_bin ${getBin glibc} \
-        --subst-var-by glibc_dev ${getDev glibc} \
-        --subst-var-by glibc_lib ${getLib glibc}
+        --subst-var-by libc_bin ${getBin cc.libc} \
+        --subst-var-by libc_dev ${getDev cc.libc} \
+        --subst-var-by libc_lib ${getLib cc.libc}
     '';
 
   meta = {