imagemagick: security bump to version 6.7.8-8

Fixes CVE-2012-3437, CVE-2012-3437 and CVE-2012-3438.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/imagemagick/imagemagick.mk

@@ -4,8 +4,8 @@
 #
 #############################################################
 
-IMAGEMAGICK_MAJOR = 6.7.6
-IMAGEMAGICK_VERSION = $(IMAGEMAGICK_MAJOR)-9
+IMAGEMAGICK_MAJOR = 6.7.8
+IMAGEMAGICK_VERSION = $(IMAGEMAGICK_MAJOR)-8
 IMAGEMAGICK_SOURCE = ImageMagick-$(IMAGEMAGICK_VERSION).tar.bz2
 # The official ImageMagick site only keeps the latest versions
 # available, which is annoying. Use an alternate site that keeps all