Revert "Update stdlib_hashmap_chaining.f90"

This reverts commit 873a6de.

Author: chuckyvt

src/stdlib_hashmap_chaining.f90

@@ -569,7 +569,7 @@ module subroutine map_chain_entry(map, key, other, conflict)
                 map % slots(hash_index) % target => new_ent
                 call copy_key( key, new_ent % key )
                 !if ( present(other) ) new_ent % other = other
-                if ( present(other) ) allocate( new_ent % other, source=other)
+                allocate( new_ent % other, source=other)
                 if ( new_ent % inmap == 0 ) then
                     map % num_entries = map % num_entries + 1
                     inmap = map % num_entries