Merge Clang debug info crash fix rev 200797:

    Debug info: fix a crasher when when emitting debug info for
    not-yet-completed templated types. getTypeSize() needs a complete type.

    rdar://problem/15931354

PR:		193347
MFC after:	3 days
Sponsored by:	DARPA, AFRL
Add clang patch for r271282

Note that r271282 contains only the src change from Clang rev 200797.
This patch file includes two follow-on changes to the test case, which
do not apply to the copy in the FreeBSD tree.

Upstream Clang revisions:

200797:

    Debug info: fix a crasher when when emitting debug info for
    not-yet-completed templated types. getTypeSize() needs a complete type.

    rdar://problem/15931354

200798:

    Simplify testcase from r200797 some more.

200805:

    Further simplify r200797 and add an explanatory comment.

PR:		193347
MFC after:	3 days
Sponsored by:	DARPA, AFRL
Include the gssapi_krb5 library in KRB5_LDFLAGS.

PR:		156245
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation