- Remove LIB_DEPENDS on libpkg.so to fix pkg-devel usage.

* While this dependency is proper, it creates a hard dependency on
    ports-mgmt/pkg, which interferes with pkg-devel testing. Users
    using pkg-devel are forced to install ports-mgmt/pkg if using this
    port or anything depending on this port.
    While the LIB_DEPENDS has been removed, pkg will still record that
    the net-snmp package requires libpkg.so.1, due to its auto shlib
    dependency registering. This is fine as the package depends on
    libpkg.so.1 but not explicitly on ports-mgmt/pkg. The pkg solver
    can decide how to satisfy that dependency.
  * If using pkg you'll already have pkg installed while building
    this port in ports or installing from packages. So nothing is lost
    here.
  * Once pkg-1.3 is out we may change ACTUAL-PACKAGE-DEPENDS to only
    consider RUN_DEPENDS, not also LIB_DEPENDS. This would remove
    the hard dependency on ports-mgmt/pkg here. pkg-1.2 cannot
    handle this yet though.

Reported by:	rpaulo
Reported at:	https://github.com/freebsd/pkg/issues/785
With hat:	portmgr

net-mgmt/net-snmp/Makefile

@@ -3,7 +3,7 @@
 
 PORTNAME=	snmp
 PORTVERSION=	5.7.2
-PORTREVISION=	7
+PORTREVISION=	8
 CATEGORIES=	net-mgmt ipv6
 MASTER_SITES=	SF/net-${PORTNAME}/net-${PORTNAME}/${PORTVERSION}
 PKGNAMEPREFIX=	net-
@@ -15,7 +15,8 @@ COMMENT=	An extendable SNMP implementation
 LICENSE=	BSD3CLAUSE
 LICENSE_FILE=	${WRKSRC}/COPYING
 
-LIB_DEPENDS=	libpkg.so:${PORTSDIR}/ports-mgmt/pkg
+# pkg-1.2 cannot handle this dependency well.
+#LIB_DEPENDS=	libpkg.so:${PORTSDIR}/ports-mgmt/pkg
 
 OPTIONS_DEFINE=	IPV6 MFD_REWRITES PERL PERL_EMBEDDED PYTHON DUMMY TKMIB \
 		DMALLOC MYSQL AX_SOCKONLY UNPRIVILEGED SMUX