By the way, using a hello world example, I obtained the following results:
$ echo 'main = putStrLn "Hello, world!"' > hello.hs
$ ghc -o hello hello.hs
[1 of 1] Compiling Main ( hello.hs, hello.o )
Linking hello ...
$ ./hello
Hello, world!
$ ls -sh ./hello
1008K ./hello
Perhaps GHC is using only a subset of the RTS, due to the limited scope of the program.
(The build target does appear to have a few dependencies, but I believe all are independent of GHC: libgmp.so.10, libm.so.6, librt.so.1, libdl.so.2, libffi.so.6, libpthread.so.0, libc.so.6).
Someone with more experience than I on the topic might comment on what, if any, significance to associate with this result.