Use C++ style comments consistently in SDL source code

Implemented using this script:

find . -type f -exec sed -i'' -e 's,/\* *\([^*]*\)\*/ *$,// \1,' -e 's, \+$,,' {} \;
git checkout \
    core/linux/SDL_evdev_kbd_default_keymap.h \
    events/imKStoUCS.* \
    hidapi \
    joystick/controller_type.c \
    joystick/controller_type.h \
    joystick/hidapi/steam/controller_constants.h \
    joystick/hidapi/steam/controller_structs.h \
    joystick/SDL_gamepad_db.h \
    libm \
    render/*/*Shader*.h \
    render/vitagxm/SDL_render_vita_gxm_shaders.h \
    render/metal/SDL_shaders_metal_*.h \
    stdlib/SDL_malloc.c \
    stdlib/SDL_qsort.c \
    stdlib/SDL_strtokr.c \
    test/ \
    video/directx/SDL_d3d12_xbox_cmacros.h \
    video/directx/d3d12.h \
    video/directx/d3d12sdklayers.h \
    video/khronos \
    video/x11/edid-parse.c \
    video/x11/xsettings-client.* \
    video/yuv2rgb
sed -i'' -e 's,/\* *\([^*]*\)\*/ *$,// \1,' -e 's, \+$,,' hidapi/SDL_hidapi.c

src/haptic/android/SDL_syshaptic.c

@@ -277,7 +277,7 @@ int Android_RemoveHaptic(int device_id)
     SDL_hapticlist_item *prev = NULL;
 
     for (item = SDL_hapticlist; item; item = item->next) {
-        /* found it, remove it. */
+        // found it, remove it.
         if (device_id == item->device_id) {
             const int retval = item->haptic ? 0 : -1;
 
@@ -291,9 +291,9 @@ int Android_RemoveHaptic(int device_id)
                 SDL_hapticlist_tail = prev;
             }
 
-            /* Need to decrement the haptic count */
+            // Need to decrement the haptic count
             --numhaptics;
-            /* !!! TODO: Send a haptic remove event? */
+            // !!! TODO: Send a haptic remove event?
 
             SDL_free(item->name);
             SDL_free(item);
@@ -304,4 +304,4 @@ int Android_RemoveHaptic(int device_id)
     return -1;
 }
 
-#endif /* SDL_HAPTIC_ANDROID */
+#endif // SDL_HAPTIC_ANDROID

src/haptic/android/SDL_syshaptic_c.h

@@ -25,4 +25,4 @@
 extern int Android_AddHaptic(int device_id, const char *name);
 extern int Android_RemoveHaptic(int device_id);
 
-#endif /* SDL_HAPTIC_ANDROID */
+#endif // SDL_HAPTIC_ANDROID