[DWARF] dwarf2out cleanups

https://gcc.gnu.org/ml/gcc-patches/2019-05/msg00485.html
	* dwarf2out.c (breakout_comdat_types): Move comment to correct
	piece of code.
	(const_ok_for_output_1): Balance parens around #if/#else/#endif
	(gen_member_die): Move abstract origin check earlier.  Only VARs
	can be static_inline_p.  Simplify splicing control flow.

From-SVN: r271127