Convert CMake-language commands to lower case

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

Modules/CMakeUnixFindMake.cmake

@@ -12,5 +12,5 @@
 # (To distribute this file outside of CMake, substitute the full
 #  License text for the above reference.)
 
-FIND_PROGRAM(CMAKE_MAKE_PROGRAM NAMES gmake make smake)
-MARK_AS_ADVANCED(CMAKE_MAKE_PROGRAM)
+find_program(CMAKE_MAKE_PROGRAM NAMES gmake make smake)
+mark_as_advanced(CMAKE_MAKE_PROGRAM)