examples/bond: fix build with clang
examples/bond: fix build with clang

Fix the following compilation error:

examples/bond/main.c:717:1: error: control reaches end of
  non-void function [-Werror,-Wreturn-type]

The prompt() function does not return anything, so fix its prototype
to be void.

Signed-off-by: Olivier Matz <dfcc1510895413197abb4336e39bb0a3906cba71@6wind.com>

mixja/dpdk,john-mcnamara-intel/dpdk,venkynv/dpdk-mirror,tsphillips/dpdk-fork,john-mcnamara-intel/dpdk,msune/dpdk,mixja/dpdk,venkynv/dpdk-mirror,mixja/dpdk,tsphillips/dpdk-fork,john-mcnamara-intel/dpdk,msune/dpdk,tsphillips/dpdk-fork,venkynv/dpdk-mirror,john-mcnamara-intel/dpdk,msune/dpdk,tsphillips/dpdk-fork,msune/dpdk,mixja/dpdk,venkynv/dpdk-mirror