MFC r355430:

ses: sanitize illegal strings in SES element descriptors

The SES4r3 standard requires that element descriptors may only contain ASCII
characters in the range 0x20 to 0x7e. Some SuperMicro expanders violate
that rule. This patch adds a sanity check to ses(4). Descriptors in
violation will be replaced by "<invalid>".

This patch fixes "sesutil --libxo xml" on such systems. Previously it would
generate non-well-formed XML output.

PR: 241929
Reviewed by: allanjude
Sponsored by: Axcient