Calling ghci also needs the linker options

For a normal compile we do separate invocations of ghc for compiling as
for linking. But for repl we have to do just the one invocation, so
that one has to include all the linker stuff too, like -l flags and any
.o files from C files etc.

Need to see how .o files from C files works with ghci that uses dynamic
loading by default.
Merge pull request #1435 from dcoutts/master

Calling ghci also needs the linker options