binutils: Add --enable-new-dtags
This option makes ld use DT_RUNPATH instead of DT_RPATH. DT_RPATH is
generally considered bad because it takes precedence over
LD_LIBRARY_PATH. For example, eog is linked with -rpath /usr/lib/eog,
and with DT_RPATH if an old eog is already installed we are basically
impossible to debug a new eog build w/o overwriting the system
installation first or explicitly using "ld.so --inhibit-rpath" to
invoke it.
This "new" actually means "new in 2000," it's 24 years ago and all other
distros has enabled it. Thus I guess some unexplainable "test suite
uses installed library instead of the just built one" issues in BLFS are
actually caused by this difference: the package author just assumes
everyone is using DT_RUNPATH thus they just set LD_LIBRARY_PATH and
consider it enough to test with the just built libraries, but DT_RPATH
breaks this expectation.
Let's eliminate the difference as it seems not doing anything good and
doing so just takes one switch.