linux: Setup valgrind

[jcfr]

Here were the flags:

set(WITH_MEMCHECK TRUE)
[...]

set(CTEST_MEMORYCHECK_SUPPRESSIONS_FILE "${CTEST_SCRIPT_DIRECTORY}/${HOSTNAME}-ubuntu_slicer4_valgrind_supression.txt")
set(CTEST_MEMORYCHECK_COMMAND_OPTIONS "--gen-suppressions=all --trace-children=yes -q --leak-check=yes --show-reachable=yes --num-callers=100")
set(ADDITIONAL_CMAKECACHE_OPTION "
  CMAKE_C_COMPILER:FILEPATH=/usr/bin/gcc-4.6
  CMAKE_CXX_COMPILER:FILEPATH=/usr/bin/g++-4.6
  MEMORYCHECK_COMMAND:FILEPATH=${CTEST_MEMORYCHECK_COMMAND}
  MEMORYCHECK_SUPPRESSIONS_FILE:FILEPATH=${CTEST_MEMORYCHECK_SUPPRESSIONS_FILE}
  MEMORYCHECK_COMMAND_OPTIONS:STRING=${CTEST_MEMORYCHECK_COMMAND_OPTIONS}
  Slicer_BUILD_CLI:BOOL=ON
  Slicer_USE_PYTHONQT_WITH_OPENSSL:BOOL=ON
")

The factory-south-ubuntu_slicer4_valgrind_supression.txt file in the repository was empty when this issue was created.

[jcfr]

This is mostly completed, see Slicer/Slicer@3d663f3 Slicer/Slicer@2480d9b