Fix installation of crosstool-ng libraries to target

When using the crosstool-ng toolchain option, the libc libraries were not
installed to target.  Buildroot calls the show-tuple function to determine
the directory to copy from, and it seems that outputs the result to stderr
instead of stdout

Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>