maintainer-feedback requested: [Bug 274697] editors/libreoffice: fix build with lld 17

From: <bugzilla-noreply_at_freebsd.org>
Date: Tue, 24 Oct 2023 16:25:06 UTC
Bugzilla Automation <bugzilla@FreeBSD.org> has asked FreeBSD Office Team
<office@FreeBSD.org> for maintainer-feedback:
Bug 274697: editors/libreoffice: fix build with lld 17
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=274697



--- Description ---
Building editors/libreoffice with lld 17 results in the following link
errors:

  ld: error: version script assignment of 'PRIVATE_1.4' to symbol
'_ZN3sal13backtrace_getEm' failed: symbol not defined
  ld: error: version script assignment of 'GLIBCXX_3.4' to symbol
'_ZNSs4_Rep20_S_empty_rep_storageE' failed: symbol not defined

Upstream fixed this only for Linux with:
https://github.com/LibreOffice/core/commit/baddc742c3fe260d20d7924ab134f0fbf179
fd85

Add the same block to the more generic unxgcc.mk makefile, so it gets
picked up for FreeBSD too.