NO-OP: fix some Wimplicit-fallthrough

gcc can recognize various regexps in comments. Since C++17 provides
[[fallthrough]], using /* fallthrough */ consistently seems
appropriate until we switch to C++17.

see also https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html

libs/appleutility/CoreAudio/AudioUnits/AUPublic/AUCarbonViewBase/AUCarbonViewControl.cpp

@@ -327,6 +327,7 @@ bool	AUCarbonViewControl::HandleEvent(EventHandlerCallRef inHandlerRef, EventRef
 				case kEventControlSetFocusPart:	// tab
 					handled = !handled;		// fall through to next case
 					mLastControl = this;
+					/* fallthrough */
 				case kEventControlValueFieldChanged:
 					GetEventParameter(event, kEventParamDirectObject, typeControlRef, NULL, sizeof(ControlRef), NULL, &control);
 					verify(control == mControl);

libs/ardour/session_state.cc

@@ -2446,7 +2446,7 @@ retry:
 
 				case 3:
 					no_questions_about_missing_files = true;
-					/* fallthru */
+					/* fallthrough */
 
 				case -1:
 				default:

libs/backends/portaudio/winmmemidi_output_device.cc

@@ -432,10 +432,10 @@ WinMMEMidiOutputDevice::midi_output_thread ()
 		switch (h.size) {
 		case 3:
 			message |= (((DWORD)data[2]) << 16);
-		// Fallthrough on purpose.
+			/* fallthrough */
 		case 2:
 			message |= (((DWORD)data[1]) << 8);
-		// Fallthrough on purpose.
+			/* fallthrough */
 		case 1:
 			message |= (DWORD)data[0];
 			result = midiOutShortMsg (m_handle, message);

libs/clearlooks-newer/clearlooks_style.c

@@ -726,11 +726,13 @@ clearlooks_style_draw_box (DRAW_ARGS)
 				{
 					case GTK_PROGRESS_RIGHT_TO_LEFT:
 						tmp.x -= 1;
+						/* fallthrough */
 					case GTK_PROGRESS_LEFT_TO_RIGHT:
 						tmp.width += 1;
 						break;
 					case GTK_PROGRESS_BOTTOM_TO_TOP:
 						tmp.y -= 1;
+						/* fallthrough */
 					case GTK_PROGRESS_TOP_TO_BOTTOM:
 						tmp.height += 1;
 						break;

libs/evoral/src/Curve.cpp

@@ -322,7 +322,8 @@ Curve::_get_vector (double x0, double x1, float *vec, int32_t veclen) const
 					// any discrete vector curves somewhere?
 					assert (0);
 				case ControlList::Curved:
-					// fallthrough, no 2 point spline
+					/* no 2 point spline */
+					/* fallthrough */
 				default: // Linear:
 					for (int i = 0; i < veclen; ++i) {
 						vec[i] = (lx * (m_num / m_den) + m_num * i * dx_num / (m_den * dx_den)) + c;
@@ -342,7 +343,8 @@ Curve::_get_vector (double x0, double x1, float *vec, int32_t veclen) const
 					// any discrete vector curves somewhere?
 					assert (0);
 				case ControlList::Curved:
-					// fallthrough, no 2 point spline
+					/* no 2 point spline */
+					/* fallthrough */
 				default: // Linear:
 					vec[0] = interpolate_linear (lval, uval, fraction);
 					break;

libs/gtkmm2ext/keyboard.cc

@@ -400,7 +400,7 @@ Keyboard::leave_window (GdkEventCrossing *ev, Gtk::Window* /*win*/)
 
 		case GDK_NOTIFY_VIRTUAL:
 			DEBUG_TRACE (DEBUG::Keyboard, "VIRTUAL crossing ... out\n");
-			/* fallthru */
+			/* fallthrough */
 
 		default:
 			DEBUG_TRACE (DEBUG::Keyboard, "REAL crossing ... out\n");

libs/midi++2/parser.cc

@@ -493,9 +493,10 @@ Parser::scanner (unsigned char inbyte)
 
 	case NEEDTWOBYTES:
 		/* wait for the second byte */
-		if (msgindex < 3)
+		if (msgindex < 3) {
 			return;
-		/*FALLTHRU*/
+		}
+		/* fallthrough */
 
 	case NEEDONEBYTE:
 		/* We've completed a 1 or 2 byte message. */

libs/surfaces/faderport8/faderport8.cc

@@ -959,7 +959,7 @@ FaderPort8::filter_stripables (StripableList& strips) const
 			break;
 		default:
 			assert (0);
-			// fall through
+			/* fallthrough */
 		case MixAll:
 			allow_master = true;
 			flt = &flt_all;

libs/surfaces/osc/osc.cc

@@ -1816,49 +1816,56 @@ OSC::surface_parse (const char *path, const char* types, lo_arg **argv, int argc
 				} else {
 					linkid = argv[8]->i;
 				}
+				/* fallthrough */
 			case 8:
 				if (types[7] == 'f') {
 					linkset = (int) argv[7]->f;
 				} else {
 					linkset = argv[7]->i;
 				}
+				/* fallthrough */
 			case 7:
 				if (types[6] == 'f') {
 					port = (int) argv[6]->f;
 				} else {
 					port = argv[6]->i;
 				}
+				/* fallthrough */
 			case 6:
 				if (types[5] == 'f') {
 					pi_page = (int) argv[5]->f;
 				} else {
 					pi_page = argv[5]->i;
 				}
+				/* fallthrough */
 			case 5:
 				if (types[4] == 'f') {
 					se_page = (int) argv[4]->f;
 				} else {
 					se_page = argv[4]->i;
 				}
+				/* fallthrough */
 			case 4:
 				if (types[3] == 'f') {
 					fadermode = (int) argv[3]->f;
 				} else {
 					fadermode = argv[3]->i;
 				}
+				/* fallthrough */
 			case 3:
 				if (types[2] == 'f') {
 					feedback = (int) argv[2]->f;
 				} else {
 					feedback = argv[2]->i;
 				}
-				// [[fallthrough]]; old compiler doesn't like
+				/* fallthrough */
 			case 2:
 				if (types[1] == 'f') {
 					strip_types = (int) argv[1]->f;
 				} else {
 					strip_types = argv[1]->i;
 				}
+				/* fallthrough */
 			case 1:
 				if (types[0] == 'f') {
 					bank_size = (int) argv[0]->f;

tools/luadevel/devel.cc

@@ -158,7 +158,8 @@ class LuaTableRef {
 						/* fallthrough */
 					case LUA_TFUNCTION: // no support -- we could... string.format("%q", string.dump(value, true))
 					case LUA_TTABLE: // no nested tables, sorry.
-					case LUA_TNIL: // fallthrough
+					case LUA_TNIL:
+						/* fallthrough */
 					default:
 						// invalid value
 						lua_pop (L, 2);