ykclient: remove pointless PKG_BUILD_DEPENDS

Also replace dependency with + one.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

utils/ykclient/Makefile

@@ -2,15 +2,15 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=ykclient
 PKG_VERSION:=2.15
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE:=ykclient-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://developers.yubico.com/yubico-c-client/Releases/
 PKG_HASH:=f461cdefe7955d58bbd09d0eb7a15b36cb3576b88adbd68008f40ea978ea5016
+
 PKG_MAINTAINER:=Stuart B. Wilkins <stuwilkins@mac.com>
 PKG_LICENSE_FILES:=COPYING
 PKG_LICENSE:=BSD-2-Clause
-PKG_BUILD_DEPENDS:=curl
 
 include $(INCLUDE_DIR)/package.mk
 
@@ -19,7 +19,7 @@ define Package/ykclient
   CATEGORY:=Utilities
   TITLE:=The Yubico yubikey c client library
   URL:=https://developers.yubico.com/yubico-c-client/
-  DEPENDS:=curl
+  DEPENDS:=+curl
 endef
 
 define Package/ykclient/description