tests: fix false failure for test referencing libdl

* init.cfg (gcc_shared_): -ldl has to be positioned after the object
files that may rely upon it.  This fixes tests/cp/nfs-removal-race.sh
which references dlsym() from libdl.

init.cfg

@@ -521,7 +521,7 @@ gcc_shared_()
   local out=$2
   shift 2 || return 1
 
-  $CC -Wall -shared --std=gnu99 -fPIC -ldl -O2 $* "$in" -o "$out"
+  $CC -Wall -shared --std=gnu99 -fPIC -O2 $* "$in" -o "$out" -ldl
 }
 
 # There are a myriad of ways to build shared libs,