common/rc: support compressed module files

common/rc: support compressed module files

The commit 8017ea524367 ("common/rc: ensure modules are loadable in
_have_modules()") introduced a helper function _module_file_exists()
which assumes module files have extension ".ko". However, the assumption
is not true when module files are compressed. In this case, extensions
of modules files have abbreviations of compression algorithm such as
".ko.xz",".ko.gz" or ".ko.zstd". This results in module file existence
check failure and unexpected test skips.

Fix this by changing module file search condition to cover module file
extensions with the compression algorithm abbreviations.

Fixes: 8017ea524367 ("common/rc: ensure modules are loadable in _have_modules()")
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://github.com/osandov/blktests/issues/101