Hadrian builds a lot more than make after changing just the RTS

Rebuilding GHC after just changing a file in the RTS is fast as it just builds the C file and then relinks. Hadrian compiles a lot more after modifying one of the C files in rts which takes at least 5 minutes with the prof flavour.

It should be investigated why Hadrian compiles so much more when it isn't necessary to do so much recompilation.