Merge clang r322390 into 6.0 branch: [Lex] Avoid out-of-bounds dereference in LexAngledStringLiteral.

[vsapsai]

Bugzilla Link	35954
Resolution	FIXED
Resolved on	Jan 17, 2018 08:30
Version	6.0
OS	All
Blocks	#35152
CC	@zmodem

Extended Description

This commit https://reviews.llvm.org/rC322390 fixes stack buffer overflow discovered by OSS-Fuzz https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=3832

[zmodem]

It was merged in r322649.