Added the following utility methods to VarDecl that provide

canonicalized queries of a variable's storage:

  hasAutoStorage - Does a variable have (implicit) auto storage?

  hasStaticStorage - Does a variable have (implicit) static storage?

  hasLocalStorage - Is the variable a non-static local variable?

  hasGlobalStorage - Is the variable a global variable or a static
                     local variable?

Additional comments documenting these functions are included in the
source.

llvm-svn: 41092