Fix bug 25362 "cppcoreguidelines-pro-bounds-array-to-pointer-decay does not consider const"

Summary:
The current matcher is
  implicitCastExpr(unless(hasParent(explicitCastExpr())))
but the AST in the bug is
  `-CXXStaticCastExpr 0x2bb64f8 <col:21, col:55> 'void *const *'
static_cast<void *const *> <NoOp>
    `-ImplicitCastExpr 0x2bb64e0 <col:47> 'void *const *' <NoOp>
      `-ImplicitCastExpr 0x2bb64c8 <col:47> 'void **'
<ArrayToPointerDecay>
        `-DeclRefExpr 0x2bb6458 <col:47> 'void *[2]' lvalue Var
0x2bb59d0 'addrlist' 'void *[2]'
i.e. an ImplicitCastExpr (const cast) between decay and explicit cast.

Reviewers: alexfh, sbenza, bkramer, aaron.ballman

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D14517

llvm-svn: 253399