Show the log file to make it easy to follow progress

[eregon]

• Fixes Can the install command have --verbose by default #1721

[eregon]

Example output:

$ ruby-build 2.3.7 ~/.rubies/ruby-2.3.7
To follow progress, use 'tail -f /tmp/ruby-build.20220806124059.87425.log' or pass --verbose
Downloading openssl-1.0.2u.tar.gz...
-> https://dqw8nmjcqpjn7.cloudfront.net/ecd0c6ffb493dd06707d38b14bb4d8c2288bb7033735606569d8f90f89669d16
Installing openssl-1.0.2u...
Installed openssl-1.0.2u to /home/eregon/.rubies/ruby-2.3.7

Downloading ruby-2.3.7.tar.bz2...
-> https://cache.ruby-lang.org/pub/ruby/2.3/ruby-2.3.7.tar.bz2
Installing ruby-2.3.7...

WARNING: ruby-2.3.7 is past its end of life and is now unsupported.
It no longer receives bug fixes or critical security updates.

[eregon]

Done here and not in build_package to avoid to output it twice e.g. when also installing openssl.