* stdlib/fmtmsg.c (fmtmsg): Change output format slightly to make
it look better and bring it closer to SysV behavior.
* stdlib/Makefile (distribute): Add tst-fmtmsg.sh.
(test-srcs): Add tst-fmtmsg.
(tests): Add $(objpfx)tst-fmtmsg.out. Add rule to generate it.
* stdlib/tst-fmtmsg.sh: New file.
* stdlib/tst-fmtmsg.c: New file.