COMP: Build test CLIs only if BUILD_TESTING is ON

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22836 3bd1e089-480b-0410-8dfb-8563597acbee
COMP: Fix 'ninja' build error specifying 'make' command to build OpenSSL.

Since OpenSSL build system doesn't provide ninja files, it is important
to explicitly specify that it should be built using ninja.

Error was the following:

[7/9] Performing build step for 'Slicer'
FAILED: cd /home/jchris/Projects/SarrpTPS-SuperBuild-Release-Qt485-N/Slicer-build && /home/jchris/Support/cmake-2.8.11.2/bin/cmake --build /home/jchris/Projects/SarrpTPS-SuperBuild-Release-Qt485-N/Slicer-build --config . && /home/jchris/Support/cmake-2.8.11.2/bin/cmake -E touch /home/jchris/Projects/SarrpTPS-SuperBuild-Release-Qt485-N/CMake/Superbuild/Slicer-cmake/src/Slicer-stamp/Slicer-build
ninja: error: build.ninja:726: bad $-escape (literal $ must be written as $$)

ninja: build stopped: subcommand failed.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22837 3bd1e089-480b-0410-8dfb-8563597acbee
COMP: Fix VTK external project to work correctly with Ninja generator

Use the variable 'CMAKE_MAKE_PROGRAM' instead of the undocumented variable
MAKECOMMAND.

For more details referers to CMake commits kitware/CMake@4ac75fdf [1] and
kitware/CMake@4cce44b [2]

This is know to work with:
 - Ninja 1.4.0
 - CMake 2.8.12.1

[1] http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=4ac75fdf
[2] http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=4cce44b

The error was:

// ---------------
FAILED: cd /home/jchris/Projects/SarrpTPS-SuperBuild-Release-Qt485-N/Slicer-build/VTK-build && /home/jchris/Support/cmake-2.8.11.2/bin/cmake -DMAKE_COMMAND= -P /home/jchris/Projects/SarrpTPS-SuperBuild-Release-Qt485-N/Slicer-build/VTK_build_step.cmake && /home/jchris/Support/cmake-2.8.11.2/bin/cmake -E touch /home/jchris/Projects/SarrpTPS-SuperBuild-Release-Qt485-N/Slicer-build/VTK-prefix/src/VTK-stamp/VTK-build
CMake Error at /home/jchris/Projects/SarrpTPS-SuperBuild-Release-Qt485-N/Slicer-build/VTK_build_step.cmake:5 (message):
  error: MAKE_COMMAND is not set !
// ---------------

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22838 3bd1e089-480b-0410-8dfb-8563597acbee