Fix runpath handling for FreeBSD 10+ and DragonFly 3.2+.

LD_LIBRARY_PATH no longer overrides DT_RPATH.

DragonFly 4f0bc915b65fc and FreeBSD r238471 changed the runtime linker to
search order to DT_RPATH, LD_LIBRARY_PATH, DT_RUNPATH, etc. It used to
be LD_LIBRARY_PATH, DT_RPATH|DT_RUNPATH as these were aliased.

This issue is seen by running a test suite from a checkout that has its
own shared library while also having an older version of that library
in /usr/lib. The test would use the wrong library.

diff --git m4/libtool.m4 m4/libtool.m4
index f2d1f398..ac21a3b3 100644
--- m4/libtool.m4
+++ m4/libtool.m4
@@ -2715,10 +2715,15 @@ freebsd* | dragonfly*)
     shlibpath_overrides_runpath=no
     hardcode_into_libs=yes
     ;;
-  *) # from 4.6 on, and DragonFly
+  freebsd4.[[6-9]] | freebsd[[56789]].[[0-9]]* | dragonfly[[12]].[[0-9]]* | \
+  dragonfly3.[[01]]*)
     shlibpath_overrides_runpath=yes
     hardcode_into_libs=yes
     ;;
+  *) # from FreeBSD 10.0 on, and DragonFly 3.2 on
+    shlibpath_overrides_runpath=no
+    hardcode_into_libs=yes
+    ;;
   esac
   ;;