imagemagick: bump version to 7.0.3-7 (security)

oss-security reference:
  http://www.openwall.com/lists/oss-security/2016/11/13/1

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/imagemagick/imagemagick.hash

@@ -1,2 +1,2 @@
 # From http://www.imagemagick.org/download/releases/digest.rdf
-sha256 86a1f04077de2b1486a93088030b010780067b25ab0284560435e2f458e247ca ImageMagick-7.0.3-4.tar.xz
+sha256 140b99f33a3326aed92132a7cd054ee962a6e2562064c68495640411aa4571d7  ImageMagick-7.0.3-7.tar.xz

package/imagemagick/imagemagick.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-IMAGEMAGICK_VERSION = 7.0.3-4
+IMAGEMAGICK_VERSION = 7.0.3-7
 IMAGEMAGICK_SOURCE = ImageMagick-$(IMAGEMAGICK_VERSION).tar.xz
 IMAGEMAGICK_SITE = http://www.imagemagick.org/download/releases
 IMAGEMAGICK_LICENSE = Apache-2.0