frontend: Remove unused macOS window icons

Commit [1] originally made a differentiation between the operating
systems for the window icon. However, on macOS the window icon is only
respected for the main window (and used for the entire app, as windows
themselves don't have icons), and that got removed in [2]. This means
that this code doesn't actually do anything anymore, and thus should be
removed.

[1] 9ac92f61beec573794fc5cb33299a62b448e4bb0
[2] 4afafaac6dbfc3e083e3602f20301cacf31da6b5

frontend/forms/obs.qrc

@@ -13,7 +13,6 @@
     <file>images/plus.svg</file>
     <file>images/down.svg</file>
     <file>images/up.svg</file>
-    <file>images/obs_256x256.png</file>
     <file>images/obs.png</file>
     <file>images/obs_macos.svg</file>
     <file>images/obs_paused.png</file>

frontend/widgets/OBSBasicStats.cpp

@@ -169,9 +169,7 @@ OBSBasicStats::OBSBasicStats(QWidget *parent, bool closable)
 	resize(800, 280);
 
 	setWindowTitle(QTStr("Basic.Stats"));
-#ifdef __APPLE__
-	setWindowIcon(QIcon::fromTheme("obs", QIcon(":/res/images/obs_256x256.png")));
-#else
+#ifndef __APPLE__
 	setWindowIcon(QIcon::fromTheme("obs", QIcon(":/res/images/obs.png")));
 #endif
 

frontend/widgets/OBSProjector.cpp

@@ -42,9 +42,7 @@ OBSProjector::OBSProjector(QWidget *widget, obs_source_t *source_, int monitor,
 #endif
 
 	type = type_;
-#ifdef __APPLE__
-	setWindowIcon(QIcon::fromTheme("obs", QIcon(":/res/images/obs_256x256.png")));
-#else
+#ifndef __APPLE__
 	setWindowIcon(QIcon::fromTheme("obs", QIcon(":/res/images/obs.png")));
 #endif