Filesystem blocks are of size `f_frsize` (#17493)

The statvfs(3) manpage on Linux states that `f_blocks` is the "size of fs in `f_frsize` units".  The manpages on Solaris and AIX state something similar.

With ext4 on Linux, I suspect that `f_bsize` and `f_frsize` are always identical, masking this error.  On Solaris, the sizes differ for each of ufs, vxfs and zfs causing the `size_available` and `size_total` facts to be set incorrectly on this OS.

lib/ansible/module_utils/facts.py

@@ -581,8 +581,8 @@ class Facts(object):
         size_available = None
         try:
             statvfs_result = os.statvfs(mountpoint)
-            size_total = statvfs_result.f_bsize * statvfs_result.f_blocks
-            size_available = statvfs_result.f_bsize * (statvfs_result.f_bavail)
+            size_total = statvfs_result.f_frsize * statvfs_result.f_blocks
+            size_available = statvfs_result.f_frsize * (statvfs_result.f_bavail)
         except OSError:
             pass
         return size_total, size_available