lib: utils: Switch matches() to returning int again

lib: utils: Switch matches() to returning int again

Since commit 1f420318bda3 ("utils: don't match empty strings as prefixes")
the function has pretended to return a boolean. But every user expects it
to return zero on success and a non-zero value on failure, like strcmp().
Even the function itself actually returns "true" to mean "no match". This
only makes sense if one considers a boolean to be a one-bit unsigned
integer with no inherent meaning, which I do not think is reasonable.

Switch the prototype back to int, and return 1 instead of true.

Cc: Matteo Croce <mcroce@redhat.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David Ahern <dsahern@kernel.org>