Fix -o flag separator type

[Jake-Shadle]

When I tried to enable sccache for native compilation in addition to rust I ran into errors (the same kind as #189), I found that ring was causing sccache to fail because it's a bit more involved in the use of cc and when specifying the output object file is just directly concatenating the flag and the arg, so the command ends up being

$ "scccache" "gcc" blah blah blah "-c" "-o/somepathto.o" "somepathto.c"

Just changing the type of separator to support both -ofile or -o file allowed sccache to compile ring successfully.

Resolves: #189

[luser]

Gosh, compiler options are weird, aren't they?