Remove "pure" and "pure_none" calling conventions

core/odin/ast/ast.odin

@@ -22,9 +22,7 @@ Proc_Calling_Convention :: enum i32 {
 	C_Decl,
 	Std_Call,
 	Fast_Call,
-	Pure,
 	None,
-	Pure_None,
 
 	Foreign_Block_Default = -1,
 }

core/odin/parser/parser.odin

@@ -1907,13 +1907,8 @@ string_to_calling_convention :: proc(s: string) -> ast.Proc_Calling_Convention {
 	case "fast", "fastcall":
 		return .Fast_Call;
 
-	case "pure":
-		return .Pure;
 	case "none":
 		return .None;
-	case "pure_none":
-		return .Pure_None;
-
 	}
 	return .Invalid;
 }