contrib: qtsvg: remove no longer needed patch

From testing, it seems that the qtsvg build retrieves zlib.h from
$(PREFIX)/include/QtZlib/zlib.h. Its directory is specified with the -I
flag. The $(PREFIX)/include directory is specified with the -isystem
flag, which has lower priority than -I. So $(PREFIX)/include/zlib.h has
the lowest priority, and the patch is not needed anymore.

qtbase also includes plain <zlib.h>, but qtbase already has -I flags
pointing directly to the vendored zlib directory in the source tree.

contrib/src/qtsvg/0001-Force-the-usage-of-QtZlib-header.patch

-From ed55cab9836d8ed9a4738c795855b0b2af6fa6b9 Mon Sep 17 00:00:00 2001
-From: Pierre Lamot <pierre@videolabs.io>
-Date: Thu, 21 Sep 2017 12:05:15 +0200
-Subject: [PATCH] Force the usage of QtZlib header
-
-  qmake adds -I$(PREFIX)/include before adding
-  -I$(PREFIX)/include/QtZlib in its path while cross
-  compiling which ends up using the definition from the
-  system zlib while linking to QtZlib
----
- src/svg/qsvgtinydocument.cpp | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
-diff --git a/src/svg/qsvgtinydocument.cpp b/src/svg/qsvgtinydocument.cpp
-index cc0fd5d..450c2d1 100644
---- a/src/svg/qsvgtinydocument.cpp
-+++ b/src/svg/qsvgtinydocument.cpp
-@@ -45,7 +45,7 @@
- #include "qdebug.h"
- 
- #ifndef QT_NO_COMPRESS
--#include <zlib.h>
-+#include <QtZlib/zlib.h>
- #endif
- 
- QT_BEGIN_NAMESPACE
--- 
-2.14.1
-

contrib/src/qtsvg/rules.mak

@@ -21,7 +21,6 @@ $(TARBALLS)/qtsvg-everywhere-src-$(QTSVG_VERSION).tar.xz:
 
 qtsvg: qtsvg-everywhere-src-$(QTSVG_VERSION).tar.xz .sum-qtsvg
 	$(UNPACK)
-	$(APPLY) $(SRC)/qtsvg/0001-Force-the-usage-of-QtZlib-header.patch
 	$(MOVE)
 
 .qtsvg: qtsvg