fix incorrect users for temps resulting from casting the result of ?:

There are probably other situations, but I'll fix them as they show up.

tools/qfcc/include/expr.h

@@ -191,6 +191,7 @@ expr_t *new_param_expr (struct type_s *type, int num);
 expr_t *new_move_expr (expr_t *e1, expr_t *e2, struct type_s *type);
 
 void inc_users (expr_t *e);
+void dec_users (expr_t *e);
 void convert_name (expr_t *e);
 
 expr_t *append_expr (expr_t *block, expr_t *e);

tools/qfcc/source/constfold.c

@@ -151,7 +151,14 @@ convert_to_float (expr_t *e)
 		case ex_uexpr:
 		case ex_temp:
 		case ex_block:
-			return cast_expr (&type_float, e);
+			e = cast_expr (&type_float, e);
+			// The expression of which this is a sub-expression has already 
+			// incremented users, so we don't need cast_expr to do so again,
+			// however, since cast_expr does so unconditionally, we must undo
+			// the increment.
+			if (e && e->type == ex_uexpr && e->e.expr.op == 'C')
+				dec_users (e->e.expr.e1);
+			return e;
 		default:
 			internal_error (e);
 	}

tools/qfcc/source/expr.c

@@ -336,6 +336,15 @@ inc_users (expr_t *e)
 		inc_users (e->e.block.result);
 }
 
+void
+dec_users (expr_t *e)
+{
+	if (e && e->type == ex_temp)
+		e->e.temp.users--;
+	else if (e && e->type == ex_block)
+		dec_users (e->e.block.result);
+}
+
 expr_t *
 new_expr (void)
 {