build: Add DESTDIR to make

Add the variable DESTDIR that allows a user to install into
a directory that will later be moved to another host. This
facilitates the creation of distribution packages.

  make DESTDIR=/tmp/build prefix=/usr install

Will install the program files into /tmp/build/usr/..
but the program will expect to find itself in the /usr/..
directories.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2 files changed