git: use pcre2

[l2dy]

Description

Fixes: https://trac.macports.org/ticket/54568

With pcre2 @10.30

/opt/local/bin/git:
	/opt/local/lib/libpcre2-8.0.dylib (compatibility version 7.0.0, current version 7.0.0)
	/opt/local/lib/libz.1.dylib (compatibility version 1.0.0, current version 1.2.11)
	/opt/local/lib/libiconv.2.dylib (compatibility version 9.0.0, current version 9.0.0)
	/opt/local/lib/libintl.8.dylib (compatibility version 10.0.0, current version 10.5.0)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1226.10.1)

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 10.12
Xcode 8.3.3

Verification

Have you

• followed our Commit Message Guidelines?
• 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?

[macportsbot]

Notifying maintainers:
@ci42 for port git.

By a harmless bot.