Fix testsuite_linux.sh to separate program output and valgrind errors

[byllyfish]

...for versions of valgrind that don't recognize the statx system call.

This could be implemented by stubbing out exacl as a shell function.

testsuite_linux.sh
==================
# MEMCHECK=valgrind -q --error-exitcode=9 --leak-check=full --errors-for-leak-kinds=definite
testReadAclFromMissingFile
testReadAclForFile1
testReadAclForDir1
testReadAclForLink1
testWriteAclToMissingFile
ASSERT:expected:<File "/tmp/shunit.z5s5xB/tmp/non_existant": required ACL entry is missing> but was:<--7359-- WARNING: unhandled amd64-linux syscall: 332
--7359-- You may be able to write your own handler.
--7359-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--7359-- Nevertheless we consider this a bug.  Please report
--7359-- it at http://valgrind.org/support/bug_reports.html.
File "/tmp/shunit.z5s5xB/tmp/non_existant": required ACL entry is missing>
testWriteAclToFile1
ASSERT:expected:<File "/tmp/shunit.z5s5xB/tmp/file1": required ACL entry is missing> but was:<--7375-- WARNING: unhandled amd64-linux syscall: 332
--7375-- You may be able to write your own handler.
--7375-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--7375-- Nevertheless we consider this a bug.  Please report
--7375-- it at http://valgrind.org/support/bug_reports.html.
File "/tmp/shunit.z5s5xB/tmp/file1": required ACL entry is missing>