editors/emacs26: Fix ImageMagick option

[Anthony Mallet <anthony.mallet%laas.fr@localhost>]

Hi,

I noticed that emacs configured with imagemagick option wants
ImageMagick-6, not 7, hence the following patch (compiled & tested).
Without the patch, the option is silently ignored by emacs configure
script.

diff -u -r1.12 options.mk
--- editors/emacs26/options.mk  5 Sep 2019 13:04:55 -0000       1.12
+++ editors/emacs26/options.mk  26 Oct 2020 18:23:02 -0000
@@ -93,7 +93,7 @@
 ### Support ImageMagick (not recognized for now, sorry)
 ###
 .  if !empty(PKG_OPTIONS:Mimagemagick)
-.include "../../graphics/ImageMagick/buildlink3.mk"
+.include "../../graphics/ImageMagick6/buildlink3.mk"
 # DEPENDS+=    py[0-9]*-wand-[0-9]*:../../graphics/py-wand
 .  else
 CONFIGURE_ARGS+=       --without-imagemagick