testsuite: test358 is unreliable on Debian s390x

[rdmark]

test358 in the testsuite is unreliable when running on s390x specifically. This has been observed 2 out of 14 runs so far in the Debian debci autopkgtest environment.

############## entering test358 ##############
[FPOpenVolFull] Open Vol test1 bitmap 21
[FPCreateDir] Create Directory Vol 1 did : 0x2 <t358 dir>
directory ID 0x14c
[FPCreateFile] Create File SOFT Vol 1 did : 0x14c <t358 file>
[FPCreateFile] Create File SOFT Vol 1 did : 0x14c <t358 file user 2>
[FPGetFileDirParams] GetFileDirParams Vol 1 did : 0x14c <>
[FPGetFileDirParams] GetFileDirParams Vol 1 did : 0x14c <>
[FPSetFilDirParam] Set FilDirParam 0x14c <> bitmap 0x1001
[FPGetFileDirParams] GetFileDirParams Vol 1 did : 0x14c <>
[FPEnumerateFull] Enumerate Vol 1 did : 0x14c <> sindex: 1 reqcnt: 5
[FPEnumerateFull] Enumerate Vol 1 did : 0x14c <> sindex: 1 reqcnt: 5
header.dsi_code       -5000 AFPERR_ACCESS  
[FPSetDirParms] Set DirParam 0x14c  bitmap 0x1000
[FPDelete] FPDelete conn 2ed32370 Vol 1 did : 0x14c <t358 file>
[FPDelete] FPDelete conn 2ed32370 Vol 1 did : 0x14c <t358 file user 2>
[FPDelete] FPDelete conn 2ed32370 Vol 1 did : 0x14c <>
header.dsi_code       -5032 AFPERR_OLOCK   
[../test/testsuite/FPSetFileDirParms.c:951] FPDelete(Conn, vol, dir , "")
    FAILED
FPSetFileDirParms:test358: set unix access privilege two users - FAILED

[rdmark]

The workaround in https://github.com/Netatalk/netatalk/pull/1741 was not sufficient.

[rdmark]

Attempted to reproduce in a qemu emulated s390x environment, via Docker and Debian Testing. All 20 runs were successful in this controlled environment. There must be a resource constraint, or race condition, unique to debci runners.