Before this commit, makefiles under tools/ directory
were implemented with their own way.
This commit refactors them by using "hostprogs-y" variable.
Several C sources have been added to wrap other C sources
to simplify Makefile.
For example, tools/crc32.c includes lib/crc32.c
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>