Bump minimum Qt version to 5.6.2

Starting to use macos qmake scope. 5.6.3 should be around soon so
we can still regression test latest two patch levels.

Change-Id: I14f67a26e26c50f6dd0fb8b621f13780b0b05f76
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

README.md

@@ -14,7 +14,7 @@ The standalone binary packages support the following platforms:
 
 Prerequisites:
 
-* Qt 5.6.0 or later
+* Qt 5.6.2 or later
 * Qt WebEngine module for QtWebEngine based help viewer
 * On Windows:
     * ActiveState Active Perl

qbs/imports/QtcPlugin.qbs

@@ -12,7 +12,7 @@ QtcProduct {
     property var pluginRecommends: []
     property var pluginTestDepends: []
 
-    property string minimumQtVersion: "5.6.0"
+    property string minimumQtVersion: "5.6.2"
     condition: QtcFunctions.versionIsAtLeast(Qt.core.version, minimumQtVersion)
 
     targetName: QtcFunctions.qtLibraryName(qbs, name)

qtcreator.pro

@@ -1,9 +1,9 @@
 include(qtcreator.pri)
 
 #version check qt
-!minQtVersion(5, 6, 0) {
+!minQtVersion(5, 6, 2) {
     message("Cannot build Qt Creator with Qt version $${QT_VERSION}.")
-    error("Use at least Qt 5.6.0.")
+    error("Use at least Qt 5.6.2.")
 }
 
 include(doc/doc.pri)