test(parser): pin the trailing comment of a TEXT and GLOBL header

Assisted-by: GLM 5.3 Flash

parser/flags.go

@@ -62,8 +62,10 @@ var flagOrder = []struct {
 	{"ABIWRAPPER", 4096},
 }
 
-// flagsRun prepares one flags operand for evaluation: the comments are
-// dropped, they are layout the expression never sees.
+// flagsRun strips the comments from one flags operand.  A comment on a
+// directive line is always its trailing text (a comment mid-line is the
+// statement boundary the statement reader makes of it), so what the
+// operand split hands over carries it at the tail at most.
 func flagsRun(g []token.Token) []token.Token {
 	out := make([]token.Token, 0, len(g))
 	for _, t := range g {