[llvm-pdbdump] Fix dumping of function pointers and basic types.

Function pointers were not correctly handled by the dumper, and
they would print as "* name".  They now print as
"int (__cdecl *name)(int arg1, int arg2)" as they should.

Also, doubles were being printed as floats.  This fixes that bug
as well, and adds tests for all builtin types. as well as a test
for function pointers.

llvm-svn: 230703