RED-579: SNOW-751: 'configure' with cmake 2.8 is extremely slow.

Note that indra/cmake/CMakeLists.txt is missing on imprudence, so
I couldn't add 'FindZLIB.cmake' to the list of source files
(see
http://svn.secondlife.com/trac/linden/browser/projects/2009/snowglobe/trunk/indra/cmake/CMakeLists.txt)

I added a comment to
http://github.com/mccabe/imprudence/commit/39f625963e408ec5dd394e202506700259b9b508
that adds an empty indra/cmake/CMakeLists.txt

If Jacek follows up and copies snowglobe's CMakeLists.txt then she'll
have to remove the FindZLIB.cmake from it if she tests it before
merging with THIS commit. In that case it has to be added back when
merging that commit with this one.

Tested on imprudence with cmake 2.8.2:
* Without patch, 'configure' takes 100 seconds.
* With patch, 'configure' takes 4 seconds.

2 files changed, 48 insertions, 0 deletions

diff --git a/linden/doc/contributions.txt b/linden/doc/contributions.txt
index eee1774..cff6863 100644
--- a/linden/doc/contributions.txt
+++ b/linden/doc/contributions.txt
@@ -58,6 +58,7 @@ Aleric Inglewood
         SNOW-479
         SNOW-626
         SNOW-744
+        SNOW-751
         SNOW-766
         SNOW-800
         RED-552
@@ -75,6 +76,7 @@ Aleric Inglewood
         RED-576
         RED-577
         RED-578
+        RED-579
 Alissa Sabre
         VWR-81
         VWR-83
diff --git a/linden/indra/cmake/FindZLIB.cmake b/linden/indra/cmake/FindZLIB.cmake
new file mode 100644
index 0000000..6d630f1
--- /dev/null
+++ b/linden/indra/cmake/FindZLIB.cmake
@@ -0,0 +1,46 @@
+# -*- cmake -*-
+
+# - Find zlib
+# Find the ZLIB includes and library
+# This module defines
+#  ZLIB_INCLUDE_DIRS, where to find zlib.h, etc.
+#  ZLIB_LIBRARIES, the libraries needed to use zlib.
+#  ZLIB_FOUND, If false, do not try to use zlib.
+#
+# This FindZLIB is about 43 times as fast the one provided with cmake (2.8.x),
+# because it doesn't look up the version of zlib, resulting in a dramatic
+# speed up for configure (from 4 minutes 22 seconds to 6 seconds).
+#
+# Note: Since this file is only used for standalone, the windows
+# specific parts were left out.
+
+FIND_PATH(ZLIB_INCLUDE_DIR zlib.h
+  NO_SYSTEM_ENVIRONMENT_PATH
+  )
+
+FIND_LIBRARY(ZLIB_LIBRARY z)
+
+if (ZLIB_LIBRARY AND ZLIB_INCLUDE_DIR)
+  SET(ZLIB_INCLUDE_DIRS ${ZLIB_INCLUDE_DIR})
+  SET(ZLIB_LIBRARIES ${ZLIB_LIBRARY})
+  SET(ZLIB_FOUND "YES")
+else (ZLIB_LIBRARY AND ZLIB_INCLUDE_DIR)
+  SET(ZLIB_FOUND "NO")
+endif (ZLIB_LIBRARY AND ZLIB_INCLUDE_DIR)
+
+if (ZLIB_FOUND)
+  if (NOT ZLIB_FIND_QUIETLY)
+        message(STATUS "Found ZLIB: ${ZLIB_LIBRARIES}")
+        SET(ZLIB_FIND_QUIETLY TRUE)
+  endif (NOT ZLIB_FIND_QUIETLY)
+else (ZLIB_FOUND)
+  if (ZLIB_FIND_REQUIRED)
+        message(FATAL_ERROR "Could not find ZLIB library")
+  endif (ZLIB_FIND_REQUIRED)
+endif (ZLIB_FOUND)
+
+mark_as_advanced(
+  ZLIB_LIBRARY
+  ZLIB_INCLUDE_DIR
+  )
+