company-pseudo-tooltip-frontend: Properly adjust starting column
so tooltip stays within window bounds.

* company.el:

(company--create-line-overlay): When tooltip width is equal to
window-width the last `move-to-column' would have already moved
point to next line, in which case don't move down again.

(company--adjust-column): New function.

(company-pseudo-tooltip-show, company-pseudo-tooltip-edit): Use
adjusted column instead of desired column.

(company-pseudo-tooltip-hide-line): Clear `line-prefix' and
`wrap-prefix' overlay properties.