pkgtools/pkglint: update to 19.4.10

Changes since 19.4.9:

In continuation lines with long values, pkglint no longer suggests to
move the continuation backslash in the middle of the variable value, as
that would be impossible.

Warn when a shell command is assigned to a variable that only takes
pathnames. Shell commands can contain command line options, and these
are not pathnames.

The TOOLS_PLATFORM.tool variables are not defined on every platform.
When these variables are used outside an OPSYS check, a warning lists
the platforms where the tool is undefined or only defined conditionally.

(rillig)