package/imagemagick: add prompt for host variant

Sometimes, it is required to call imagemagick from a post-build script
or the likes, so we have to allow the user to enable the host variant
for imagemagick.

Update the linux package to select the host variant now.

Signed-off-by: "Yann E. MORIN" <yann.morin@orange.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/imagemagick/Config.in.host

@@ -0,0 +1,13 @@
+config BR2_PACKAGE_HOST_IMAGEMAGICK
+	bool "host imagemagick"
+	help
+	  ImageMagick(R) is a software suite to create, edit, and
+	  compose bitmap images. It can read, convert and write images
+	  in a variety of formats (about 100) including DPX, EXR, GIF,
+	  JPEG, JPEG-2000, PDF, PhotoCD, PNG, Postscript, SVG, and TIFF.
+	  Use ImageMagick to translate, flip, mirror, rotate, scale,
+	  shear and transform images, adjust image colors, apply various
+	  special effects, or draw text, lines, polygons, ellipses and
+	  Bézier curves.
+
+	  http://www.imagemagick.org/