devtools: allow custom set of examples in build test
devtools: allow custom set of examples in build test

To test the installation process of DPDK using "ninja install"
test-meson-builds.sh builds a subset of the examples using "make". To allow
more flexibility for people testing, allow the set of examples chosen for
this make test to be overridden using variable "DPDK_BUILD_TEST_EXAMPLES"
in the environment.

Since a number of example apps link against drivers directly even for
shared builds, we need to ensure that LD_LIBRARY_PATH points to the main
DPDK lib folder so any dependencies of those drivers can be found e.g. that
the PCI/vdev bus driver .so is found. [All drivers are symlinked from
drivers dir back to lib dir on install, so only one dir rather than two is
needed in the path.]

Signed-off-by: Bruce Richardson <66b9e8e8fbd5e9f41f91b0af050876182ce9d0e4@intel.com>
Acked-by: David Marchand <f28529695cfa9e3e1eb84e7072aa626af4abb18e@redhat.com>
Acked-by: Thomas Monjalon <5f50a84c1fa3bcff146405017f36aec1a10a9e38@monjalon.net>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk