doctor: Add check for install_name_tool

Closes #29593.
Fix some places where encoding issues manifest on ruby 2.0
gnupg2 2.0.23

Update to latest stable release, update patch, change single quotes to
double quotes, and use https on the homepage link.

Closes #29842.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
gpg-agent 2.0.23

Update to latest stable release, update patch, change single quotes to
double quotes, and use https in homepage link.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
mpc 0.26

This is a bugfix release.

Closes #29848.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>