qpdf: security bump to version 8.1.0

Fixes CVE-2018-9918: mishandle certain "expected dictionary key but
found non-name object" cases, allowing remote attackers to cause a
denial of service (stack exhaustion)

https://github.com/qpdf/qpdf/issues/202

Drop local SHA256 hash since we use upstream provided SHA512.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/qpdf/qpdf.hash

@@ -1,4 +1,2 @@
-# From https://sourceforge.net/projects/qpdf/files/qpdf/7.0.0/qpdf-7.0.0.sha512/download
-sha512	7b52d67b4d2c428a7b0c1cd03b03a23f05d38d7e3c81041079a137919019ea5158f12bf95fdcfcff6b43ffdefe93a85127ced2a363a6b4b380cbaa02a3840256  qpdf-7.0.0.tar.gz
-# Locally computed
-sha256	fed08de14caad0fe5efd148d9eca886d812588b2cbb35d13e61993ee8eb8c65f  qpdf-7.0.0.tar.gz
+# From https://sourceforge.net/projects/qpdf/files/qpdf/8.1.0/qpdf-8.1.0.sha512/download
+sha512	1831bcaaed87dae268db5d61805d1483ec5c101f6ce594be660664c119597ae67cf011c2b50092964d785a814d5f6c780935127a89401fe37a1026ae4d3af15c  qpdf-8.1.0.tar.gz

package/qpdf/qpdf.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-QPDF_VERSION = 7.0.0
+QPDF_VERSION = 8.1.0
 QPDF_SITE = http://downloads.sourceforge.net/project/qpdf/qpdf/$(QPDF_VERSION)
 QPDF_INSTALL_STAGING = YES
 QPDF_LICENSE = Artistic-2.0