Silence compilation warnings

[tsujan]

Most of them say AUTOMOC: CMAKE_AUTOMOC_RELAXED_MODE is deprecated....

One of them says,

CMake Warning (dev) at /usr/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:441 (message):
  The package name passed to `find_package_handle_standard_args` (PkgConfig)
  does not match the name of the calling package (QJSON).  This can lead to
  problems in calling code that expects `find_package` result variables
  (e.g., `_FOUND`) to follow a certain pattern.
Call Stack (most recent call first):
  /usr/share/cmake/Modules/FindPkgConfig.cmake:114 (find_package_handle_standard_args)
  cmake/modules/FindQJSON.cmake:19 (include)
  tools/CMakeLists.txt:1 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.