Use libbsdyml is exists instead of bundled libyaml

Conflicts:
	libpkg/Makefile
	libpkg/pkg_ports.c
SRV_MIRRORS was reworked to MIRROR_TYPE in fac3243e
Fix ABI support in PACKAGESITE causing assertion

pkg: pkg_init() must be called before pkg_config_int64()

This must be called after 'parsed' is true since it accesses
ABI from the config.
Default MIRROR_TYPE should be (1) for SRV since the default PACKAGSITE requires SRV

Broken since dc9e2406
Fix SRV mirroring support not actually looking up SRV record

Broken since dc9e2406