RFC: Use program_transform_name correctly

[Felix Lee]

Jim Blandy <jimb@redhat.com>:
> !       t='$(program_transform_name)'; echo runtest | sed -e '' $$t; \

it looks to me like this is written for a program_transform_name
that's a concatenated list of -e options.  the -e '' will keep
sed from complaining if program_transform_name is null.

I remember at some point in the past, sometimes
program_transform_name was a semicolon-separated list of sed
commands, sometimes it was a list of sed -e options.  Don't know
if it's consistent now.
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