Fixed a bug in which the DWARF reader did not distinguish

appropriately between C++ static methods and non-static
methods.  This bug made it impossible to call most static
methods, either because Clang did not recognize that a
method could be called without providing a "this"
parameter, or because Clang did not properly mangle the
name of the method when searching for it in the target.

Also added a testcase.

llvm-svn: 136733