libxmlsec: remove xmlsec1-nssmangleciphers.patch.1

This was added in commit ebd1b95b
(INTEGRATION: CWS xmlsec08 (1.1.2); FILE ADDED, 2005-03-10). According
to CWS history it was introduced in the 1.1.2.1 part, without any
further comments.

Before the gbuild conversion in commit
ec6af419 (convert libxmlsec to gbuild,
2012-11-29) the makefile.mk had a comment for this patch: "Dubious, do
we still need this ?".

My best guess is that this was added as part of some effort to do ODF
encryption (not just signing) in xmlsecurity, but code for that on the
xmlsecurity part is already removed.

Change-Id: I3a5f1fedd7ce10b8b874bb8a3c9e6260213fbd8f
Reviewed-on: https://gerrit.libreoffice.org/37261Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

external/libxmlsec/UnpackedTarball_xmlsec.mk

@@ -10,7 +10,6 @@
 xmlsec_patches :=
 xmlsec_patches += xmlsec1-configure.patch.1
 xmlsec_patches += xmlsec1-nssdisablecallbacks.patch.1
-xmlsec_patches += xmlsec1-nssmangleciphers.patch.1
 xmlsec_patches += xmlsec1-noverify.patch.1
 xmlsec_patches += xmlsec1-vc.patch.1
 xmlsec_patches += xmlsec1-1.2.14_fix_extern_c.patch.1