meson: options: Add an option to control compilation of qcam

Add an option to control compilation of the qcam test application. The
default behavior is to compile qcam, no change in behavior without user
intervention.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/qcam/meson.build

@@ -22,7 +22,7 @@ qt5 = import('qt5')
 qt5_dep = dependency('qt5',
                      method : 'pkg-config',
                      modules : ['Core', 'Gui', 'Widgets'],
-                     required : false)
+                     required : get_option('qcam'))
 
 if qt5_dep.found()
     qcam_deps = [