Minor changes to Ada tests for gnat-llvm

I found a few more spots where a minor modification to a test lets it
pass with gnat-llvm:

* For array_subcript_addr, gnat-llvm was not putting the array into
  memory.  Making the array larger works around this.

* For bp_inlined_func, it is normal for gnat-llvm to sometimes emit a
  call to an out-of-line copy of the function, so accept this.

* For null_overload and type-tick-size, I've applied the usual fix for
  keeping an unused local variable alive.