Revert "MokManager: stop using StrnCat"
Revert "MokManager: stop using StrnCat"

This reverts commit 6aa5a62515d62139a2d3b34626fac8910e864a3d.

Everything Hans said was correct.  But StrnCat() is in gnu-efi 3.0.8,
and using just StrCpy() here confuses coverity.  I'd rather have a CI
page that's not completely full of chaff, but a little bit of redundancy
in the code.

Signed-off-by: Peter Jones <2e0a021e603479ff81838c00c3b770daca4e0214@redhat.com>

rhinstaller/shim,rhinstaller/shim,rhinstaller/shim