Fix install Makefile target

The install target fails like this:

[penberg@tux libtrading]$ make install
  CC       libtrading-config.o
  LINK     libtrading-config
  INSTALL
removed `/home/penberg/bin/libtrading-config'
`libtrading-config' -> `/home/penberg/bin/libtrading-config'
removed `/home/penberg/lib/libtrading.a'
`libtrading.a' -> `/home/penberg/lib/libtrading.a'
install: invalid option -- 'l'
Try `install --help' for more information.
make: *** [install] Error 1

Fix up TEST_PROGRAM libraries properly and remove "-lz" from LIBS.

Signed-off-by: Pekka Enberg <penberg@kernel.org>