opencv3: update to 3.4.14; fix paths in pkgconfig

[mascguy]

Description

• Update opencv3 to 3.4.14
• Fix paths in generated pkgconfig

Fixes: https://trac.macports.org/ticket/62462
Fixes: https://trac.macports.org/ticket/61908

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 10.12.6 16G2136
Xcode 9.2 9C40b

macOS 10.13.6 17G14019
Xcode 10.1 10B61

macOS 10.14.6 18G103
Xcode 11.3.1 11C505

macOS 10.15.6 19G2021
Xcode 12.0 12A7209

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?
• tried existing tests with sudo port test?
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?

[mascguy]

I'm not sure why, but the Big Sur CI job was cancelled for whatever reason. Otherwise, it looks like the CI jobs have passed.

[cjones051073]

Yeah, the macOS11 CI seems to be doing this a lot at the moment..

[mascguy]

Thanks Chris!