send-email: only 'require' instead of 'use' Net::SMTP
send-email: only 'require' instead of 'use' Net::SMTP

This was proposed by Eric Wong and fixes the test. (Of course, git-send-email
does not work, if there is no Net::SMTP here, but it will say what is wrong
when you actually try to use send-email.)

Signed-off-by: Johannes Schindelin <b4cf3b77c95aaa57254d96e276bf14cfc9472402@gmx.de>
Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git