Otherwise the syntax is incorrect when the variable is empty.

Add an architecture-specific library directory path suffix for each
component.  Use different search path for SDL_sound.  Project files in
VisualC directory suggest that a win32lib will hold the libraries.
Reported-by: Paul Hampson <Paul.Hampson@Pobox.com>

Run the convert-help.bash script to convert documentation:

 ./convert-help.bash "/path/to/CMake-build/bin"

Then remove it.

Also add a comment explaining the purpose of the include/SDL* path
suffixes.  As explained in commit 7cb51739 (FindSDL: Restore
accidentally dropped search paths (#13651), 2012-11-05) the include/SDL*
path suffixes are for looking in the ENV{SDLDIR} location.
Inspired-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

Cleanup in commit 9ed24c53 (FindSDL: Remove from find_... calls PATHS
that are set by default, 2012-09-04) accidentally dropped some search
paths.  Restore the dropped PATH_SUFFIXES and add more suffixes needed
to search paths that were previously hard-coded.
Reported-by: Gino van den Bergen <gino@dtecta.com>

Use PATH_SUFFIXES to add SDL parts to standard paths.

Especially remove "lib64" when the given paths are all Unix ones and "lib" is
also explicitely given. In that case CMake will search "lib64" anyway for
platforms where it is known to make sense.

Instead of directly passing $ENV{SOMEVAR} to a find_* call pass in ENV SOMEVAR.
This will make sure the paths will get correctly handled through different
platforms, especially on Windows.

Also fixes one place where paths with windows delimiters (\) were hardcoded to
use forward slashes.

Ancient versions of CMake required else(), endif(), and similar block
termination commands to have arguments matching the command starting the
block.  This is no longer the preferred style.

Run the following shell code:

for c in else endif endforeach endfunction endmacro endwhile; do
    echo 's/\b'"$c"'\(\s*\)(.\+)/'"$c"'\1()/'
done >convert.sed &&
git ls-files -z -- bootstrap '*.cmake' '*.cmake.in' '*CMakeLists.txt' |
egrep -z -v '^(Utilities/cm|Source/kwsys/)' |
egrep -z -v 'Tests/CMakeTests/While-Endwhile-' |
xargs -0 sed -i -f convert.sed &&
rm convert.sed

Ancient CMake versions required upper-case commands.  Later command
names became case-insensitive.  Now the preferred style is lower-case.

Run the following shell code:

cmake --help-command-list |
grep -v "cmake version" |
while read c; do
    echo 's/\b'"$(echo $c | tr '[:lower:]' '[:upper:]')"'\(\s*\)(/'"$c"'\1(/g'
done >convert.sed &&
git ls-files -z -- bootstrap '*.cmake' '*.cmake.in' '*CMakeLists.txt' |
egrep -z -v '^(Utilities/cm|Source/kwsys/)' |
xargs -0 sed -i -f convert.sed &&
rm convert.sed

Our Git commit hooks disallow modification or addition of lines with
trailing whitespace.  Wipe out all remnants of trailing whitespace
everywhere except third-party code.

Run the following shell code:

git ls-files -z -- \
 bootstrap doxygen.config '*.readme' \
 '*.c' '*.cmake' '*.cpp' '*.cxx' \
 '*.el' '*.f' '*.f90' '*.h' '*.in' '*.in.l' '*.java' \
 '*.mm' '*.pike' '*.py' '*.txt' '*.vim' |
egrep -z -v '^(Utilities/cm|Source/(kwsys|CursesDialog/form)/)' |
egrep -z -v '^(Modules/CPack\..*\.in)' |
xargs -0 sed -i 's/ \+$//'

This adds copyright/license notification blocks CMake's find-modules.
Many of the modules had no notices at all.  Some had notices referring
to the BSD license already.  This commit normalizes existing notices and
adds missing notices.

Also removed some superfluous search paths.

  - The find_* commands now provide a HINTS option.
  - The option specifies paths to be preferred over the system paths.
  - Many Find* modules were using two find calls with NO_DEFAULT_PATH
    to approximate the behavior, but that blocked users from overriding
    things with CMAKE_PREFIX_PATH.
  - This commit uses the HINTS feature to get desired behavior in
    only one find command call.

BUG: Remove references to CMAKE_PREFIX_PATH variable.  It should not be referenced directly by FIND_* command calls.  The commands search it automatically.

BUG: FindSDL now has flag it responds to so it will not find/link against SDLmain. This is required to build libraries instead of applications since they don't have main().
ENH: All modules have a predictable search order, where environmental variables are searched before system paths. This is designed to make automation easier for those that need to automatically build projects without intervention but may be using alternative install locations for isolated testing.
ENH: New modules for OpenSceneGraph, Freetype, GDAL, Lua, QuickTime, GIFLIB, Producer, OpenThreads.
STYLE: Added documentation explaining peculuar SDL_LIBRARY_TEMP variable in SDL
  module when library find is incomplete.

ENH: add second failure message parameter to
FIND_PACKAGE_HANDLE_STANDARD_ARGS(), so cmake modules can specify their own
better failure messages. If the default is ok use "DEFAULT_MSG".
Do this also for FindBoost.cmake (#5349)

Alex

ENH: use the new FIND_PACKAGE_HANDLE_STANDARD_ARGS() macro in most of the
not-too-complicated modules
-remove unnecessary default search paths used in the FIND_XXX() calls

Alex

ENH: Removing extra 64-bit search paths.  They are now constructed automatically from the paths listed.