GIT_SILENT: as discussed with david, activate flags only when we use git repo

CMakeLists.txt

@@ -92,7 +92,10 @@ find_package(KF5NewStuff ${KF5_MIN_VERSION} CONFIG REQUIRED)
 set( SharedMimeInfo_MINIMUM_VERSION "1.3" )
 find_package(SharedMimeInfo ${SharedMimeInfo_MINIMUM_VERSION} REQUIRED)
 
-add_definitions(-DQT_DISABLE_DEPRECATED_BEFORE=0x060000)
+if (EXISTS "${CMAKE_SOURCE_DIR}/.git")
+   add_definitions(-DQT_DISABLE_DEPRECATED_BEFORE=0x060000)
+endif()
+
 
 # allow to disable GHNS support on resource-constrained systems
 option( ACCOUNTWIZARD_NO_GHNS "Disable GHNS support in the account wizard" FALSE )