PR 15231: import bare DW_TAG_lexical_block

PR 15231: import bare DW_TAG_lexical_block

Local variables in lambdas are not accessible
https://sourceware.org/bugzilla/show_bug.cgi?id=15231

GDB: read_lexical_block_scope
  /* Ignore blocks with missing or invalid low and high pc attributes.  */
[...]
  if (!dwarf2_get_pc_bounds (die, &lowpc, &highpc, cu, NULL))
    return;

But sometimes there is:

FAIL: gcc-5.3.1-6.fc23.x86_64
 <2><92>: Abbrev Number: 11 (DW_TAG_lexical_block)
 <3><9c>: Abbrev Number: 13 (DW_TAG_structure_type)
    <9d>   DW_AT_name        : (indirect string, offset: 0x3c): <lambda()>
    [...]

Where DW_TAG_lexical_block has no attributes.  Such whole subtree is currently
dropped by GDB while I think it should just import all its children DIEs.

It even XFAIL->XPASSes gdb.ada/out_of_line_in_inlined.exp:
	commit 0fa7fe506c242b459c4c05d331e7c7d66fb52390
	Author: Joel Brobecker <brobecker@adacore.com>
	    out of line functions nested inside inline functions.
So I have removed that xfail.

gdb/ChangeLog
2016-05-30  Jan Kratochvil  <jan.kratochvil@redhat.com>

	PR c++/15231
	* dwarf2read.c (enum pc_bounds_kind): Add PC_BOUNDS_INVALID.
	(process_psymtab_comp_unit_reader, read_func_scope): Adjust callers.
	(read_lexical_block_scope): Import DIEs from bare DW_TAG_lexical_block.
	(read_call_site_scope): Adjust callers.
	(dwarf2_get_pc_bounds): Implement pc_bounds_invalid.
	(dwarf2_get_subprogram_pc_bounds, get_scope_pc_bounds): Adjust callers.

gdb/testsuite/ChangeLog
2016-05-30  Jan Kratochvil  <jan.kratochvil@redhat.com>

	PR c++/15231
	* gdb.ada/out_of_line_in_inlined.exp: Remove xfails.
	* gdb.dwarf2/dw2-lexical-block-bare.exp: New file.