Fix nested if statements that don't have following whitespace

When trying to skip over nested if statements, if there was no whitespace
after an "if", then that "if" would not be recognized. That's a problem since
"if(" and "if{" are also valid ways to start an if statement. This change
will make it so that they are recognized correctly.

test/asm/nested-if.asm

@@ -0,0 +1,18 @@
+if 0
+	if(1)
+	endc
+	if 1
+	endc
+	if{x}
+	endc
+endc
+
+if 1
+else
+	if(1)
+	endc
+	if 1
+	endc
+	if{x}
+	endc
+endc