Avoid add M exec-opt twice

[bootleq]

Hi, when using iced repl command,
sometimes I need to use different aliases with clj -M exec option,
for example iced repl -M:xx:yy:iced,
but it produces another -M in MAIN_FLAG handling and makes the prior no-effect.

This PR try to detect -M in command line options and avoid second -M as an fix.

[liquidz]

@bootleq Thanks for your contribution!
Looks good to me, but just sorry, could you fix the following file instead of bin/iced ?

vim-iced/clj/template/iced.bash

Lines 404 to 408 in ed226c7

	if [ "$(printf '%s\n' "$MIN_MAIN_VERSION" "$CLOJURE_CLI_VERSION" | sort -V | head -n1)" = "$MIN_MAIN_VERSION" ]; then
	MAIN_FLAG="-M -m"
	else
	MAIN_FLAG="-m"
	fi

bin/iced is generated by this template file via make bin command.
It may be good to add notes about this to the head of template file.

[bootleq]

Hi, thanks for the reminder, I have changed the template, too.

Feel uncertain to add note to template, because someone didn't notice the file like me, will also overlook the note.

[liquidz]

@bootleq Thank you!

Feel uncertain to add note to template, because someone didn't notice the file like me, will also overlook the note.

If we add notes to the template and run make bin, bin/iced will also have same notes.

So it should help to avoid overlooking.

[bootleq]

If we add notes to the template and run make bin, bin/iced will also have same notes.

So it should help to avoid overlooking.

Understand, how about this comment?

# This file is generated by `make bin`.

[liquidz]

It might be helpful to specify what action to take if someone want to make a change.
e.g.

# === WARNING ===
# bin/iced is generated by `make bin`.
# Please edit clj/template/iced.bash instead of bin/iced.

[bootleq]

Thanks, I have added the comment, hope further contributors will find those files were changed together.

[liquidz]

@bootleq Thank you so much! LGTM