Handle VS-16 correctly for non-emoji codepoints

Handle VS-16 correctly for non-emoji codepoints

* admin/unidata/blocks.awk: Remove emoji overrides for codepoints with
Emoji_Presentation = No, they're no longer necessary.
* lisp/composite.el: Remove #xFE0F (VS-16) from the range handled by
`compose-gstring-for-variation-glyph' so it can be handled by
`font_range'.
* src/composite.c (syms_of_composite): New variable
`auto-composition-emoji-eligible-codepoints'.
* admin/unidata/emoji-zwj.awk: Generate value for
`auto-composition-emoji-eligible-codepoints'.  Add
`composition-function-table' entries for 'codepoint + U+FE0F' for
them.
* src/font.c (codepoint_is_emoji_eligible): New function to check if
we should try to use the emoji font for a codepoint.
(font_range): Use it.