qFatal: unify the code path for aborting via std::abort

[ChangeLog][QtCore][Important behavior changes] qFatal will now
use std::abort to terminate the application on all operating
systems. Previously, ::abort() or ::exit(1) were called, depending
on the operating system.

Change-Id: I43da912cce1db3c2229568da25000ea80060eed9
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/global/qglobal.cpp

@@ -4479,7 +4479,7 @@ bool QInternal::activateCallbacks(Callback cb, void **parameters)
     On QNX the message is sent to slogger2
 
     If you are using the \b{default message handler} this function will
-    abort on Unix systems to create a core dump. On Windows, for debug builds,
+    abort to create a core dump. On Windows, for debug builds,
     this function will report a _CRT_ERROR enabling you to connect a debugger
     to the application.
 

src/corelib/global/qlogging.cpp

@@ -140,6 +140,8 @@ static QT_PREPEND_NAMESPACE(qint64) qt_gettid()
 #endif
 #endif // !QT_BOOTSTRAPPED
 
+#include <cstdlib>
+
 #include <stdio.h>
 
 QT_BEGIN_NAMESPACE
@@ -1676,11 +1678,7 @@ static void qt_message_fatal(QtMsgType, const QMessageLogContext &context, const
     Q_UNUSED(message);
 #endif
 
-#if (defined(Q_OS_UNIX) || defined(Q_CC_MINGW))
-    abort(); // trap; generates core dump
-#else
-    exit(1); // goodbye cruel world
-#endif
+    std::abort();
 }