imagemagick: security bump to version 6.9.4-1

Fixes:
Fix GetNextToken() off by one error.
Check for buffer overflow in magick/draw.c/DrawStrokePolygon().
Remove support for internal ephemeral coder.

These are all related to the recent ImageTragick bundle that were
partially fixed in 6.9.3-10 as well.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/imagemagick/imagemagick.hash

@@ -1,2 +1,2 @@
 # From http://www.imagemagick.org/download/releases/digest.rdf
-sha256 e33f021c879f31703f9e620f578ccf7d221a34941589da4bbe967b16a814336a ImageMagick-6.9.3-10.tar.xz
+sha256 2ea0fef839cd5d6f134502b7cf7ee0e57a3f230b19771515d4aa44354f4c6b3b ImageMagick-6.9.4-1.tar.xz

package/imagemagick/imagemagick.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-IMAGEMAGICK_VERSION = 6.9.3-10
+IMAGEMAGICK_VERSION = 6.9.4-1
 IMAGEMAGICK_SOURCE = ImageMagick-$(IMAGEMAGICK_VERSION).tar.xz
 IMAGEMAGICK_SITE = http://www.imagemagick.org/download/releases
 IMAGEMAGICK_LICENSE = Apache-2.0