Unable to build stress-ng for ubuntu_ramfs_stress and ubuntu_stress_smoke_test on F-5.4 PowerPC ('MEMBARRIER_CMD_FLAG_CPU' undeclared )

[Po-Hsu Lin]

Issue found on P8 node dryden with Focal 5.4.0-83.93

Test suite HEAD SHA1: 41f614f

Test build failed with:
make[1]: Leaving directory '/home/ubuntu/autotest/client/tmp/ubuntu_stress_smoke_test/src/stress-ng'
stderr:
make[1]: warning: -j0 forced in submake: resetting jobserver mode.
stress-membarrier.c: In function 'stress_membarrier_exercise':
stress-membarrier.c:87:34: error: 'MEMBARRIER_CMD_FLAG_CPU' undeclared (first use in this function); did you mean 'MEMBARRIER_CMD_SHARED'?
   87 | ret = shim_membarrier((int)i, MEMBARRIER_CMD_FLAG_CPU, 0);
      | ^~~~~~~~~~~~~~~~~~~~~~~
      | MEMBARRIER_CMD_SHARED
stress-membarrier.c:87:34: note: each undeclared identifier is reported only once for each function it appears in
make[1]: *** [Makefile:397: stress-membarrier.o] Error 1
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:382: all] Error 2