[analyzer] Do not invalidate arguments when the parameter's

type is a pointer to const. (radar://10595327)

The regions corresponding to the pointer and reference arguments to
a function get invalidated by the calls since a function call can
possibly modify the pointed to data. With this change, we are not going
to invalidate the data if the argument is a pointer to const. This
change makes the analyzer more optimistic in reporting errors.
(Support for C, C++ and Obj C)

llvm-svn: 147002