* xdisp.c (underline_minimum_offset): Rename from xterm.c's

* xdisp.c (underline_minimum_offset): Rename from xterm.c's
x_underline_minimum_display_offset.
(syms_of_xdisp): Declare it here rather than in xterm.c.
* dispextern.h (underline_minimum_offset): Declare it.
* w32term.c (x_draw_glyph_string): Use it.
* xterm.c (x_underline_minimum_display_offset): Move to xdisp.c.
(syms_of_xterm): Don't declare it any more.
(x_draw_glyph_string): Adjust to the new name.

* cus-start.el (underline-minimum-offset) Rename from
x-underline-minimum-display-offset.