Relax test to allow for __attribute__((thiscall)). Under Win32 c-index-test output is

CXXMethod=foo:4:7 (unavailable) [type=int () __attribute__((thiscall))] [typekind=FunctionProto] [resulttype=int] [resulttypekind=Int] [isPOD=0]
CXXConstructor=Foo:5:3 (unavailable) [type=void () __attribute__((thiscall))] [typekind=FunctionProto] [resulttype=void] [resulttypekind=Void] [isPOD=0]

llvm-svn: 248626