opkg: update to latest git HEAD of branch openwrt-19.07

c5dccea libopkg: fix md5sum calculation
7cad0c0 opkg_verify_integrity: better logging and error conditions
14d6480 download: purge cached packages that have incorrect checksum
456efac download: factor out the logic for building cache filenames
b145030 libopkg: factor out checksum and size verification
74bac7a download: remove compatibility with old cache naming scheme

Fixes: FS#2690

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

package/system/opkg/Makefile

@@ -14,9 +14,9 @@ PKG_FLAGS:=essential
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL:=https://git.openwrt.org/project/opkg-lede.git
-PKG_SOURCE_DATE:=2020-05-07
-PKG_SOURCE_VERSION:=f2166a89b7e96e2c60002959731eebc5f45fa318
-PKG_MIRROR_HASH:=67e55cd9fb93bb5b62e2c7b11946483b5570287bd1504aa2a3886d11f8b750b9
+PKG_SOURCE_DATE:=2021-01-31
+PKG_SOURCE_VERSION:=c5dccea956b8be14eabf6ff69b331a3e9ac36749
+PKG_MIRROR_HASH:=fdf42d4ecf66ebc1aded54fa29c3eb41a0e08c2c65da56b661ad1cfb275dd548
 
 PKG_LICENSE:=GPL-2.0
 PKG_LICENSE_FILES:=COPYING