devel/binutils: configure with --enable-new-dtags

This makes binutils ld use DT_RUNPATH instead of DT_RPATH by default
for FreeBSD targets and brings it in line with LLVM ld.

The difference between the two is that DT_RUNPATH has a lower priority
than the LD_LIBRARY_PATH environment variable. This variable is used
by libtool to override DT_RUNPATH when running programs directly from
the build directory (e.g. during make test).

PR: 259446
Approved by: maintainer timeout (2 weeks)