Test failures with musl libc

[Sören Tempel]

Hello,

I am currently trying to get the gawk test suite to pass as part of the
Alpine Linux gawk package. Alpine uses musl libc instead of glibc. I
only observed two failing tests with gawk-5.1.0 which I would preferably
also get to pass on Alpine:

On x86_64 the clos1way6 test case fails with the following error:

        *** clos1way6.ok        2019-08-28 18:54:15.000000000 +0000
        --- _clos1way6  2021-02-06 11:52:29.933319277 +0000
        ***************
        *** 1,3 ****
          gawk: clos1way6.awk:5: warning: fflush: cannot flush: two-way pipe 
`cat - 1>&2; sleep 2' has closed write end
        - test1
          Bad file descriptor
        --- 1,3 ----
          gawk: clos1way6.awk:5: warning: fflush: cannot flush: two-way pipe 
`cat - 1>&2; sleep 2' has closed write end
          Bad file descriptor
        + test1

The test1 string seems to be output after the Bad file descriptor
message on musl. Maybe a difference in libc flushing behaviour, any idea
how this could be fixed?

Additionally, the following test case fails on the s390x architecture:

        *** sigpipe1.ok Wed Aug 28 18:43:58 2019
        --- _sigpipe1   Sat Feb  6 11:42:57 2021
        ***************
        *** 1,3 ****
          system
          pipe to command
        ! pipe from command
        --- 1,4 ----
          system
          pipe to command
        ! gawk: sigpipe1.awk:7: fatal: print to "yes | true" failed: Broken pipe
        ! EXIT CODE: 2

Unfortunately, I don't have access to this architecture myself and can't
properly debug this problem, so this is more of an FYI. I would,
however, be interested in fixing the clos1way6 failure on x86_64. Any
pointers on how to do so would be appreciated.

Greetings,
Sören