debuginfod: sqlite3 metrics

debuginfod: sqlite3 metrics

Add metrics for tracking sqlite3 error counts and query performance.

The former looks like a new sibling of the "error_count" family, and
is tested by dd-corrupting a live database file then triggering some
debuginfod activity.

    error_count{sqlite3="file is not a database"} 1

The latter looks like _count/_sum pairs for each type of sqlite
prepared-statement used in the code, and is grep smoke-tested.  They
should assist a sysadmin in tuning db storage.  This example shows a
6.4 ms/operation cost:

    sqlite3_milliseconds_count{step-done="rpm-file-intern"} 318
    sqlite3_milliseconds_sum{reset="rpm-file-intern"} 2033

Signed-off-by: Frank Ch. Eigler <fche@redhat.com>