ui_cocoa: promote bare binary to foreground on pre-10.6

On 10.5 Leopard, the RetroArch window now responded to mouse input
(after 23a9456) but still ignored keyboard input entirely.

ROOT CAUSE: A bare binary launched from a terminal (no .app bundle
wrapping, no Info.plist) starts as a background-only process.  The
WindowServer delivers mouse events to background processes that own
windows, but routes keystrokes only to the frontmost UI app (Finder
or the terminal emulator in this case).

Commit 6c37fb0 guards [NSApp setActivationPolicy:NSApplication-
ActivationPolicyRegular] - the Cocoa API that promotes a background
process to a foreground GUI app - behind MAC_OS_X_VERSION_10_6
because the selector doesn't exist on 10.5.  That's correct but
leaves pre-10.6 bare-binary builds with no promotion path at all,
hence no keystrokes.

FIX: fall back to the Carbon Process Manager equivalent on pre-10.6:

    ProcessSerialNumber psn = { 0, kCurrentProcess };
    TransformProcessType(&psn, kProcessTransformToForegroundApplication);

Available since 10.3 in <ApplicationServices/ApplicationServices.h>.
Per Leopard's HIServices release notes, 10.5 specifically added
support for promoting plain background processes (not just
LSUIElement / LSBackgroundOnly apps) to foreground, which covers
the bare-binary case.

On 10.6+ builds nothing changes - setActivationPolicy: is still
used.  On bundled .app builds nothing changes either - bundle
identity sets the process type at launch and the foreground
promotion is a no-op.  Bare-binary launches on 10.5 are the
only configuration affected, and they now receive keystrokes.

Author: LibretroAdmin

ui/drivers/ui_cocoa.m

@@ -34,6 +34,13 @@
 #include "cocoa/cocoa_common.h"
 #include "cocoa/apple_platform.h"
 
+#if !defined(MAC_OS_X_VERSION_10_6)
+/* Pre-10.6: need the Carbon Process Manager's TransformProcessType()
+ * to promote a bare-binary process to a foreground GUI app that
+ * receives keystrokes.  See the call site below in main() for detail. */
+#include <ApplicationServices/ApplicationServices.h>
+#endif
+
 #if defined(HAVE_COCOA_METAL)
 #include "../../gfx/common/metal_common.h"
 #endif
@@ -1445,11 +1452,26 @@ int main(int argc, char *argv[])
 #endif
       [NSApplication sharedApplication];
 #ifdef MAC_OS_X_VERSION_10_6
-      /* setActivationPolicy: and NSApplicationActivationPolicyRegular
-       * are 10.6+.  Before that, an app becomes a regular GUI app
-       * via Info.plist (CFBundlePackageType=APPL, no LSUIElement
-       * / LSBackgroundOnly), which the PPC bundle already does. */
+      /* setActivationPolicy: is 10.6+.  On Snow Leopard and later,
+       * this is the official way to promote a bare-binary background
+       * process to a regular GUI app that receives keystrokes. */
       [NSApp setActivationPolicy:NSApplicationActivationPolicyRegular];
+#else
+      /* Pre-10.6: setActivationPolicy: doesn't exist.  For bare-
+       * binary builds (no .app bundle wrapping, no Info.plist the
+       * WindowServer can consult), the process starts as a
+       * background-only app and NEVER RECEIVES KEYSTROKES.  Mouse
+       * events still reach the window, but key events go to whatever
+       * app is actually frontmost (Finder or a terminal emulator).
+       *
+       * The pre-10.6 equivalent is the Carbon Process Manager call
+       * TransformProcessType(), available since 10.3 and supporting
+       * plain background-only processes (no LSUIElement / LSBackground-
+       * Only) on 10.5+ per the Leopard HIServices release notes. */
+      {
+         ProcessSerialNumber psn = { 0, kCurrentProcess };
+         TransformProcessType(&psn, kProcessTransformToForegroundApplication);
+      }
 #endif
 
       delegate = [[RetroArch_OSX alloc] init];