[Patch, configure]: Message that Makefile being deleted on loop for multilibs

should not be set to stderr. Not an error, just info to user

Signed-off-by: David Holsgrove <david.holsgrove@xilinx.com>
[LOCAL]: Add missing declarations for xil_printf to stdio.h

for inclusion in toolchain and use in c++ apps

Signed-off-by: David Holsgrove <david.holsgrove@xilinx.com>