Allow to specify a separate install location for drivedb.h.

This prevents that update-smart-drivedb overwrites the package
installed file (Debian Bug 976696, Ubuntu Bug 1893202).

configure.ac, Makefile.am: Add '--with-drivedbinstdir' option.
update-smart-drivedb.in: Add '--install' option.
update-smart-drivedb.8.in: Document new functionality.
smartctl.8.in, smartd.8.in: Adjust path names.

git-svn-id: https://svn.code.sf.net/p/smartmontools/code/trunk@5318 4ea69e1a-61f1-4043-bf83-b5c94c648137