Fix line-move-visual's following of column in R2L lines.

Fix line-move-visual's following of column in R2L lines.

 src/simple.el (line-move-visual): When converting X pixel coordinate
 to temporary-goal-column, adjust the value for right-to-left
 screen lines.  This fixes vertical-motion, next/prev-line, etc.

 src/dispnew.c (buffer_posn_from_coords): Fix the value of the column
 returned for right-to-left screen lines.  (Before the change on
 2014-12-30, the incorrectly-computed X pixel coordinate concealed
 this bug.)