allow linux clang builds

QGCCommon.pri

@@ -27,10 +27,14 @@
 # the project file.
 
 linux {
-    linux-g++ | linux-g++-64 | linux-g++-32 {
+    linux-g++ | linux-g++-64 | linux-g++-32 | linux-clang {
         message("Linux build")
         CONFIG += LinuxBuild
         DEFINES += __STDC_LIMIT_MACROS
+		linux-clang {
+			message("Linux clang")
+			QMAKE_CXXFLAGS += -Qunused-arguments -fcolor-diagnostics
+		}
     } else : linux-rasp-pi2-g++ {
         message("Linux R-Pi2 build")
         CONFIG += LinuxBuild