fbc: internal: fix comment

src/compiler/ast-optimize.bas

@@ -1704,7 +1704,7 @@ private function hOptStrAssignment _
 		case AST_NODECLASS_DEREF
 			'' check if we can optimize to fb_StrConcatByref()
 			'' - look specifically for a = a + b where both a & b are STRINGS where we
-			''   won't necessarily know until run time if a & b could be the same descriptorknow until run time if a and b could be the same descriptor.
+			''   won't necessarily know until run time if a & b could be the same descriptor
 			'' - but don't optimize a = a + a since we must make a copy anyway
 			''
 			''