Basic heap profile support without -prof
Now that constructor info tables contain the name of the constructor, we can generate useful heap profiles without requiring the whole program and libraries to be compiled with -prof. So now, "+RTS -hT" generates a heap profile for any program, dividing the profile by constructor. It wouldn't be hard to add support for grouping constructors by module, or to restrict the profile to certain constructors/modules/packages. This means that for the first time we can get heap profiles for GHCi, which was previously impossible because the byte-code interpreter and linker don't work with -prof.