Emojis by png files in emoji_path are not drawn on xlib 1bpp and --with-imagelib=no

[tsutsui]

It looks mlterm built without imagelib complains on trying to print emojis:

mlimgloader 0 0 0 [file path] stdout (-a)
  -a: ignored.

Maybe ui_load_inline_picture() in uitoolkit/ui_picture.c calls ui_imagelib_load_file() via static load_file() with keep_aspect but in this case load_sixel() doesn't help for png emoji files unlike #93?

[arakiken]

mlimgloader doesn't support png files if gdk-pixbuf is not found. This commit support png emoji files with the use of libpng 1.6 or later. https://github.com/arakiken/mlterm/commit/0af65caa1aa6e62b6c836299c4353dca16387b56

[tsutsui]

Confirmed, at least on NetBSD/i386 10.0 and patched pkgsrc/x11/mlterm (without gdk_pixbuf2 option). Thanks!

[tsutsui]

Also confirmed on installed version: