devel/electron25: unbreak arm64 relocation in bundled ffmpeg

Enable support for the .data.rel.ro section because the arm64 assembly
code in ffmpeg depends on it.

Reported by: pkg-fallout
Obtained from: https://cgit.freebsd.org/ports/patch/www/chromium/files/patch-third__party_ffmpeg_configure?id=919638f2014d06b489db252c378714fbac038f83
MFH: 2023Q3

(cherry picked from commit 00aaf89b1317a92dc00b5dbb066005da4f948280)