package/yajl: add patch to fix static build issue

mpd's plugin soundcloud requires yajl. In static build context yajl library is
named yajl_s so linking against yajl fails:
  /bin/ld: cannot find -lyajl

Use a pull request patch [1] to let the shared and the static library
have the same name. They will be differentiated by the extension (.so or .a).

Fixes:
http://autobuild.buildroot.net/results/5ac/5acba9b0ed852512fc88e83973a3b5389e6d54be/
http://autobuild.buildroot.net/results/739/73934ad67efa121fedeaa03fdad290aa63f1485e/

[1] https://github.com/lloyd/yajl/pull/174

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/yajl/yajl.hash

@@ -1,2 +1,3 @@
 # Locally calculated
 sha256	0e78f516dc53ecce7dc073f9a9bb0343186b58ef29dcd1dad74e5e853b216dd5  yajl-2.0.4.tar.gz
+sha256	0f075b5f9a38bc02077370d4d57d12e615cfaaf7f634e3f2fc746b6582854e53  6d09f11b8fd358cab0e31b965327e64a599f9ce9.patch

package/yajl/yajl.mk

@@ -9,5 +9,6 @@ YAJL_SITE = $(call github,lloyd,yajl,$(YAJL_VERSION))
 YAJL_INSTALL_STAGING = YES
 YAJL_LICENSE = ISC
 YAJL_LICENSE_FILES = COPYING
+YAJL_PATCH = https://github.com/vriera/yajl/commit/6d09f11b8fd358cab0e31b965327e64a599f9ce9.patch
 
 $(eval $(cmake-package))