py-cvxopt: remove unnecessary pre-destroot code block

[jjstickel]

• remove unnecessary pre-destroot code block

Closes: https://trac.macports.org/ticket/68750

Description

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 13.6.2 22G320 arm64
Xcode 15.0.1 15A507

Verification

Have you

• followed our Commit Message Guidelines?
• squashed and minimized your commits?
• checked that there aren't other open pull requests for the same change?
• referenced existing tickets on Trac with full URL?
• checked your Portfile with port lint --nitpick?
• tried existing tests with sudo port test?
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?
• checked that the Portfile's most important variants haven't been broken?