build: CMake bugfixes

Fixes include:
- Handling of relative paths used as output directories
- Accepting comma separated lists of modules to enable/disable
- Echoing all CMake commands at the end of the execution of ns3 script
- More informative optional features summary output
- Replace absolute paths with relative paths in the printed CMake output for less verbose output
- Set debug build type on the CMake side to ensure ccmake doesn't crash
- Prefix INT64X64 with NS3 to indicate user switch
- Compiler version check
- Removal of verbose option
- Suppress empty enabled/disabled module tables

Features include:
- Test for installation/uninstallation of ns-3 as a CMake package
- Test importing ns-3 as a CMake package and use in a 3rd-party project
- Test to check VERSION usage
- ns3 option to enable/disable sanitizers
- Associate headers to libraries targets

src/mpi/CMakeLists.txt

@@ -21,7 +21,7 @@ set(header_files model/mpi-interface.h model/mpi-receiver.h
 set(libraries_to_link ${libcore} ${libnetwork} ${MPI_CXX_LIBRARIES})
 
 set(example_as_test_suite)
-if(${EXAMPLES_ENABLED})
+if(${ENABLE_EXAMPLES})
   set(example_as_test_suite test/mpi-test-suite.cc)
 endif()