This target enables integration into oss-fuzz. Changing invalid input return
to -1 as values other then 0/-1 are reserved by libfuzzer. Also adding the
missing __wrap_vsnprintf wrapper which is required for successful oss-fuzz
build.
Signed-off-by: Tamas K Lengyel <tamas@tklengyel.com>
Acked-by: Jan Beulich <jbeulich@suse.com>