net-snmp: add missing dependency to libpci

There's a build race condition with other packages which sometimes results in:

Package libnetsnmp is missing dependencies for the following libraries:
libpci.so.3

net/net-snmp/Makefile

@@ -40,7 +40,7 @@ define Package/libnetsnmp
 $(call Package/net-snmp/Default)
   SECTION:=libs
   CATEGORY:=Libraries
-  DEPENDS:=+libnl-tiny
+  DEPENDS:=+libnl-tiny +libpci
   TITLE:=Open source SNMP implementation (libraries)
 endef