Check for msgmerge and gperf in configure?

[Raymond Toy]

While trying to build texinfo in a Docker image, I found out that the 
Docker image didn't have gettext, gperf, or gawk installed. Took me a 
while to figure out why texinfo wasn't building.

AFAICT, these are required to build texinfo. Or at least I couldn't find 
any obvious configure option so that these aren't needed.

Should configure check that at least these programs exist? (Now, I have 
to go figure out how to get the Docker image to include these packages.)

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