[analyzer] Treat LValueBitCasts like regular pointer bit casts.

These casts only appear in very well-defined circumstances, in which the
target of a reinterpret_cast or a function formal parameter is an lvalue
reference. According to the C++ standard, the following are equivalent:

 reinterpret_cast<T&>( x)
*reinterpret_cast<T*>(&x)

[expr.reinterpret.cast]p11

llvm-svn: 158338