libjson-c: set HOST_BUILD_PREFIX

Install into STAGING_DIR_HOST rather than STAGING_DIR_HOSTPKG to make
bundle-libraries.sh happy.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

package/libs/libjson-c/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=json-c
 PKG_VERSION:=0.12.1
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION)-nodoc.tar.gz
 PKG_SOURCE_URL:=https://s3.amazonaws.com/json-c_releases/releases/
@@ -31,6 +31,7 @@ include $(INCLUDE_DIR)/host-build.mk
 
 TARGET_CFLAGS += $(FPIC) -Wno-implicit-fallthrough
 HOST_CFLAGS += -Wno-implicit-fallthrough
+HOST_BUILD_PREFIX:=$(STAGING_DIR_HOST)
 
 define Package/libjson-c
   SECTION:=libs