QLockFile: use QCoreApplication::applicationName.

Unlike qAppName, it doesn't require a QCoreApplication instance,
making QLockFile usable in destructors of global statics.
This also uses the value passed to setApplicationName if called
rather than always argv[0].

Change-Id: I40446aba410db42d7cfe6b4408878faf435246f7
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/io/qlockfile_unix.cpp

@@ -137,7 +137,7 @@ QLockFile::LockError QLockFilePrivate::tryLock_sys()
     // (otherwise we'd have to check every write call)
     // Use operator% from the fast builder to avoid multiple memory allocations.
     QByteArray fileData = QByteArray::number(QCoreApplication::applicationPid()) % '\n'
-                          % qAppName().toUtf8() % '\n'
+                          % QCoreApplication::applicationName().toUtf8() % '\n'
                           % localHostName() % '\n';
 
     const QByteArray lockFileName = QFile::encodeName(fileName);

src/corelib/io/qlockfile_win.cpp

@@ -94,7 +94,7 @@ QLockFile::LockError QLockFilePrivate::tryLock_sys()
     QByteArray fileData;
     fileData += QByteArray::number(QCoreApplication::applicationPid());
     fileData += '\n';
-    fileData += qAppName().toUtf8();
+    fileData += QCoreApplication::applicationName().toUtf8();
     fileData += '\n';
     fileData += localHostName();
     fileData += '\n';