- honor @cc@,@CLFAGS@ and @LDFLAGS@ which is important for cross compilation

- use a more generic regexp for renaming the generated rpc header includes - because the include is without subpath on darwin/ios
- make linkerstuff and so names dynamic according to @is_darwin@
- create install directorys if they don't exist
- use $(prefix) instead of $(DESTDIR) for installation
- build examples only if @ENABLE_EXAMPLES@ is set (default is on)
- rm -rf bin on clean because darwin adds directories here on compilation
- use u_int64_t for rpcgen on darwin instead of unsigned hyper (it is not known to the darwin rpcgen...)