libcpprestsdk: needs host-pkgconf

Commit d2f0a9bba400 (libcpprestsdk: fix building as a static library)
changed libcpprestsdk to use pkg-config to find the linker flags for
openssl, so ensure it is available.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libcpprestsdk/libcpprestsdk.mk

@@ -9,7 +9,7 @@ LIBCPPRESTSDK_SITE = $(call github,Microsoft,cpprestsdk,$(LIBCPPRESTSDK_VERSION)
 LIBCPPRESTSDK_LICENSE = MIT
 LIBCPPRESTSDK_LICENSE_FILES = license.txt
 LIBCPPRESTSDK_SUBDIR = Release
-LIBCPPRESTSDK_DEPENDENCIES += boost openssl zlib
+LIBCPPRESTSDK_DEPENDENCIES += host-pkgconf boost openssl zlib
 LIBCPPRESTSDK_CONF_OPTS = -DWERROR=OFF
 
 $(eval $(cmake-package))