phoneme_add_feature: rename phFORTIS to phVOICELESS to reflect its actual usage.

src/libespeak-ng/phoneme.c

 	case vcd:
 		phoneme->phflags |= phVOICED;
 		break;
-	case vls: // FIXME: This should be a phVOICELESS (!phVOICED) flag. Fortis/lenis are a different thing.
-		phoneme->phflags |= phFORTIS;
+	case vls:
+		phoneme->phflags != phVOICELESS;
 		break;
 	// invalid phoneme feature
 	default:

src/libespeak-ng/phoneme.h

 #define phARTICULATION 0xf0000
 #define phWAVE     0x01
 #define phUNSTRESSED 0x02
-#define phFORTIS   0x08
+#define phVOICELESS  0x08
 #define phVOICED   0x10
 #define phSIBILANT 0x20
 #define phNOLINK   0x40

src/libespeak-ng/setlengths.c

 					p->prepause = 15;
 			}
 
-			if (next->type == phPAUSE && prev->type == phNASAL && !(p->ph->phflags&phFORTIS))
+			if (next->type == phPAUSE && prev->type == phNASAL && !(p->ph->phflags&phVOICELESS))
 				p->prepause = 25;
 
 			if (prev->ph->phflags & phBRKAFTER)
 					if (prev->type == phNASAL)
 						p->prepause = 12;
 
-					if (prev->type == phSTOP && !(prev->ph->phflags & phFORTIS))
+					if (prev->type == phSTOP && !(prev->ph->phflags & phVOICELESS))
 						p->prepause = 0;
 				}
 			}
 			} else {
 				length_mod = tr->langopts.length_mods[next2type *10+ next->ph->length_mod];
 
-				if ((next->type == phNASAL) && (next2->type == phSTOP || next2->type == phVSTOP) && (next3->ph->phflags & phFORTIS))
+				if ((next->type == phNASAL) && (next2->type == phSTOP || next2->type == phVSTOP) && (next3->ph->phflags & phVOICELESS))
 					length_mod -= 15;
 			}