Correct newline_limit logic

core/odin/ast/ast.odin

@@ -16,16 +16,12 @@ Proc_Inlining :: enum u32 {
 	No_Inline = 2,
 }
 
-Proc_Calling_Convention :: enum i32 {
-	Invalid = 0,
-	Odin,
-	Contextless,
-	C_Decl,
-	Std_Call,
-	Fast_Call,
-	None,
-
-	Foreign_Block_Default = -1,
+Proc_Calling_Convention_Extra :: enum i32 {
+	Foreign_Block_Default,
+}
+Proc_Calling_Convention :: union {
+	string,
+	Proc_Calling_Convention_Extra,
 }
 
 Node_State_Flag :: enum {