[bug-gawk] make check hangs

[Curtis Doty]

On a system temporarily out of ptys, `make check` won't pass or fail. But will hang indefinitely--even when ptys are freed up again.

Can reproduce on macOS by opening up 127 terminals (until you can't open any more due to kern.tty.ptmx_max=127), and then run gawk tests.

$ brew install gawk
==> Using the sandbox
==> Downloading https://ftpmirror.gnu.org/gawk/gawk-4.1.4.tar.xz
Already downloaded: /Users/curtis/Library/Caches/Homebrew/gawk-4.1.4.tar.xz
==> ./configure --prefix=/usr/local/Cellar/gawk/4.1.4_1 --without-libsigsegv-prefix
==> make
==> make check
123
...hung here...even after freeing up some ptys...

Note the '123' output is spammed on the terminal and _pty1 file is empty.

I know this is a corner case on a resource-starved build host. But still it should fail the test instead of hanging indefinitely.

Not sure how to fix pty1.awk test or whether this is just an FYI instead of a fixable bug. Obviously, workaround is to free up some ptys and start over.

../C