cppcoreguidelines-pro-bounds-constant-array-index: crash for value dependent index...

cppcoreguidelines-pro-bounds-constant-array-index: crash for value dependent index in c++03 mode

Summary:
When the expression is value dependent,
isIntegerConstantExpr() crashes in C++03 mode with
 ../tools/clang/lib/AST/ExprConstant.cpp:9330: (anonymous namespace)::ICEDiag CheckICE(const clang::Expr *, const clang::ASTContext &):
  Assertion `!E->isValueDependent() && "Should not see value dependent exprs!"' failed.
In C++11 mode, that assert does not trigger.

This commit works around this in the check. We don't check
value-dependent indices and instead check their specialization.

Reviewers: alexfh, aaron.ballman

Subscribers: nemanjai, cfe-commits

Differential Revision: http://reviews.llvm.org/D22190

llvm-svn: 275461