vt: Fix contents of paste buffer for newcons.

Trim all word separators from end of line, except for last line and
only use '\r' to terminate the pasted lines as expected by TTY.

Submitted by: Ivan Quitschal <tezeka@hotmail.com>
Differential Revision: https://reviews.freebsd.org/D35552
PR: 263084
Sponsored by: NVIDIA Networking

(cherry picked from commit 5fe0a82501cb86278b9aa426c4bf11d992e95aaa)