fix typo.

	* vm_exec.h (DEBUG_END_INSN()): use `ec` instead of `th`.
	  This macro is used when `VMDEBUG > 0`.


	escape all env properly.

	* vm_backtrace.c (rb_debug_inspector_open): escape all env using
	  `rb_vm_stack_to_heap()` before making bindings.
	  [Bug #15105]

	  There is a complicated story of this issue:
	  Without this patch, IFUNC frame does not escaped. A IFUNC frame
	  points to CFUNC ep as previous ep. However, CFUNC ep can be escaped
	  because of making bindings of Ruby level frames.
	  IFUNC's ep can points to invalidated ep and `rb_iter_break()` will
	  fail. This is why `any?` fails.

	* test/-ext-/debug/test_debug.rb: add a test.


	* remove trailing spaces.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@66074 b2dd03c8-39d4-4d8f-98ff-823fe69b080e