[google] fix error caught by TREE_CHECKING (issue 5401045)

[davidxl@google.com]

Ok for google branches.

David


http://codereview.appspot.com/5401045/diff/1/gcc/dwarf2out.c
File gcc/dwarf2out.c (right):

http://codereview.appspot.com/5401045/diff/1/gcc/dwarf2out.c#newcode19777
gcc/dwarf2out.c:19777: {
Use TYPE_P (decl_context)

http://codereview.appspot.com/5401045/