Drop Window::resourceMatch()

Its body is trivial and it's used only once so it can be inlined.

src/window.cpp

@@ -193,11 +193,6 @@ void Window::setResourceClass(const QString &name, const QString &className)
     Q_EMIT windowClassChanged();
 }
 
-bool Window::resourceMatch(const Window *c1, const Window *c2)
-{
-    return c1->resourceClass() == c2->resourceClass();
-}
-
 qreal Window::opacity() const
 {
     return m_opacity;

src/window.h

@@ -666,7 +666,6 @@ public:
     ClientMachine *clientMachine() const;
     virtual bool isLocalhost() const;
     virtual pid_t pid() const;
-    static bool resourceMatch(const Window *c1, const Window *c2);
 
     bool readyForPainting() const; // true if the window has been already painted its contents
     QRegion inputShape() const;

src/x11window.cpp

@@ -3090,7 +3090,7 @@ bool X11Window::belongToSameApplication(const X11Window *c1, const X11Window *c2
                && c2->wmClientLeader() != c2->window() // don't use in this test then
                && !checks.testFlag(SameApplicationCheck::AllowCrossProcesses)) {
         ; // different client leader
-    } else if (!resourceMatch(c1, c2)) {
+    } else if (c1->resourceClass() != c2->resourceClass()) {
         ; // different apps
     } else if (!sameAppWindowRoleMatch(c1, c2, checks.testFlag(SameApplicationCheck::RelaxedForActive))
                && !checks.testFlag(SameApplicationCheck::AllowCrossProcesses)) {