options set from the command line have incorrect extra quotes added

[ryandesign (Ryan Carsten Schmidt)]

I used to be able to disable ccache for a single port build by adding configure.ccache=no to the command line invocation, but with the latest base code I now get an error:

sudo port -s install php53-vld configure.ccache=no
--->  Cleaning php53-vld
--->  Computing dependencies for php53-vld
Error: expected boolean value but got ""no""
Error: See /opt/local/var/macports/logs/_Users_rschmidt_macports_macports-ports_php_php-vld/php53-vld/main.log for details.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.
Error: Processing of port php53-vld failed

[ryandesign (Ryan Carsten Schmidt)]

Similar problem reported for inability to set configure.compiler on the command line in #53157.

[kurthindenburg (Kurt Hindenburg)]

From what I gather using git bisect, this was the commit

commit 59bceb47a4eb7ce3e354069220fbbaeba7544cf3
Author: Joshua Root <jmr@macports.org>
Date:   Wed Nov 30 08:59:01 2016 +1100

    improve quoting of 'interp eval' args

    Having a single argument, preferably braced to guarantee that no
    substitution will happen, reduces the amount of string processing
    and may enable byte compilation in some cases.

[jmroot (Joshua Root)]

In 06daa26/macports-base:

Don't overquote values of command line options

This was previously needed because they were not correctly quoted when used
elsewhere, but that was fixed.

Fixes: #53113