libmicrohttpd: make https support optional

Libmicrohttpd works nicely without https support, so make it optional.
Also ensure the cross-libgcrypt-config is found, rather than whatever
is installed on the host.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/libmicrohttpd/Config.in

@@ -1,8 +1,14 @@
 config BR2_PACKAGE_LIBMICROHTTPD
 	bool "libmicrohttpd"
-	select BR2_PACKAGE_LIBGCRYPT
 	help
 	  GNU libmicrohttpd is a small C library that makes it easy to
 	  run an HTTP server as part of another application.
 
 	  http://www.gnu.org/software/libmicrohttpd/
+
+config BR2_PACKAGE_LIBMICROHTTPD_SSL
+       bool "https support"
+       depends on BR2_PACKAGE_LIBMICROHTTPD
+       select BR2_PACKAGE_LIBGCRYPT
+       help
+         Enable HTTPS (SSL) support.

package/libmicrohttpd/libmicrohttpd.mk

@@ -8,6 +8,12 @@ LIBMICROHTTPD_SOURCE:=libmicrohttpd-$(LIBMICROHTTPD_VERSION).tar.gz
 LIBMICROHTTPD_SITE:=$(BR2_GNU_MIRROR)/libmicrohttpd
 LIBMICROHTTPD_INSTALL_STAGING = YES
 
-LIBMICROHTTPD_DEPENDENCIES = libgcrypt
+ifeq ($(BR2_PACKAGE_LIBMICROHTTPD_SSL),y)
+LIBMICROHTTPD_DEPENDENCIES += libgcrypt
+LIBMICROHTTPD_CONF_OPT += --enable-https \
+			  --with-libgcrypt-prefix=$(STAGING_DIR)/usr
+else
+LIBMICROHTTPD_CONF_OPT += --disable-https
+endif
 
 $(eval $(call AUTOTARGETS,package,libmicrohttpd))