devel/mdb: Update to a newer snapshot which builds on recent HEAD.

[jhb]

Summary

This snapshot includes fixes to build again on HEAD after the OpenZFS
import. It also fixes ::kgrep on HEAD after the changes in r346302.
Finally, it includes debug symbols in shipped binaries to ease future debugging.

Test Plan

• poudriere testport on both stable/12 and head

[jhb]

• Update to a newer snapshot that fixes kgrep and a weird /usr/local issue.
• Include debug symbols in installed files to ease debugging.

[kevans]

With the STRIP change we discussed:

Approved by: kevans (ports)

[jhb]

• Actually install debug symbols.