Remove incorrect use of PKG_SHA256SUM

OpenWRT/LEDE only understands the PKG_MD5SUM variable, and detects if the
hash is e.g. SHA256 by looking at the length of the hash.

This affects libs/libmicrohttpd, mail/ssmtp and utils/mc.

Signed-off-by: Baptiste Jonglez <git@bitsofnetworks.org>

libs/libmicrohttpd/Makefile

@@ -13,8 +13,7 @@ PKG_RELEASE:=1
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=@GNU/libmicrohttpd
-PKG_MD5SUM:=4a3f793d59f663a2b0fc62d44668fb66
-PKG_SHA256SUM:=d1b6385068abded29b6470e383287aa7705de05ae3c08ad0bf5747ac4dc6ebd7
+PKG_MD5SUM:=d1b6385068abded29b6470e383287aa7705de05ae3c08ad0bf5747ac4dc6ebd7
 
 PKG_MAINTAINER:=Alexander Couzens <lynxis@fe80.eu>
 

mail/ssmtp/Makefile

@@ -15,7 +15,7 @@ PKG_LICENSE:=GPL-2.0+
 
 PKG_SOURCE:=$(PKG_NAME)_$(PKG_VERSION).orig.tar.bz2
 PKG_SOURCE_URL:=http://ftp.debian.org/debian/pool/main/s/ssmtp
-PKG_SHA256SUM:=22c37dc90c871e8e052b2cab0ad219d010fa938608cd66b21c8f3c759046fa36
+PKG_MD5SUM:=22c37dc90c871e8e052b2cab0ad219d010fa938608cd66b21c8f3c759046fa36
 
 include $(INCLUDE_DIR)/package.mk
 

utils/mc/Makefile

@@ -15,7 +15,7 @@ PKG_LICENSE:=GPL-3.0+
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
 PKG_SOURCE_URL:=http://ftp.midnight-commander.org/
-PKG_SHA256SUM:=0447bdddc0baa81866e66f50f9a545d29d6eebb68b0ab46c98d8fddd2bf4e44d
+PKG_MD5SUM:=0447bdddc0baa81866e66f50f9a545d29d6eebb68b0ab46c98d8fddd2bf4e44d
 PKG_BUILD_PARALLEL:=1
 PKG_FIXUP:=autoreconf gettext-version