Make QtCriticalMsg exit on QT_FATAL_CRITICALS

Change-Id: I92e8f9851dd074f3bcded6981f5545d1e93b549f
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>

src/corelib/global/qglobal.cpp

@@ -3291,6 +3291,8 @@ bool QInternal::activateCallbacks(Callback cb, void **parameters)
     stderr. Under Windows, the message is sent to the debugger.
     On Blackberry the message is sent to slogger2.
 
+    It exits if the environment variable QT_FATAL_CRITICALS is not empty.
+
     This function takes a format string and a list of arguments,
     similar to the C printf() function. The format should be a Latin-1
     string.

src/corelib/global/qlogging.cpp

@@ -83,6 +83,11 @@ static bool isFatal(QtMsgType msgType)
     if (msgType == QtFatalMsg)
         return true;
 
+    if (msgType == QtCriticalMsg) {
+        static bool fatalCriticals = !qEnvironmentVariableIsEmpty("QT_FATAL_CRITICALS");
+        return fatalCriticals;
+    }
+
     if (msgType == QtWarningMsg || msgType == QtCriticalMsg) {
         static bool fatalWarnings = !qEnvironmentVariableIsEmpty("QT_FATAL_WARNINGS");
         return fatalWarnings;