qmake quiet output

-GIT_TAG is redundant
-closes mavlink#4023

QGCCommon.pri

@@ -113,8 +113,7 @@ exists ($$PWD/.git) {
     GIT_TIME     = $$system(git --git-dir $$PWD/.git --work-tree $$PWD show --oneline --format=\"%ci\" -s HEAD)
 
     # determine if we're on a tag matching vX.Y.Z (stable release)
-    GIT_TAG      = $$system(git --git-dir $$PWD/.git --work-tree $$PWD describe --exact-match --tags HEAD)
-    contains(GIT_TAG, v[0-9].[0-9].[0-9]) {
+    contains(GIT_DESCRIBE, v[0-9].[0-9].[0-9]) {
         # release version "vX.Y.Z"
         GIT_VERSION = $${GIT_DESCRIBE}
     } else {
@@ -130,7 +129,7 @@ exists ($$PWD/.git) {
         MAC_BUILD    = $$section(VERSION, ".", 3, 3)
         message(QGroundControl version $${MAC_VERSION} build $${MAC_BUILD} describe $${GIT_VERSION})
     } else {
-        message(QGroundControl version $${VERSION} describe $${GIT_VERSION})
+        message(QGroundControl $${GIT_VERSION})
     }
 } else {
     GIT_VERSION     = None