Conditionally use system provided libopenbmc_intf

This patch structures the make rules such that building from the top
will build the in-tree libopenbmc_intf and link to that.  For example:
 $make
 $make bmcctl
would both result in ../libopenbmc_intf being built and the applications
will link to that.

Alternatively when building applications directly like:
 $make -C bmcctl
the default compiler/linker search paths will be used.

The latter facilitates package managers and the former retains a level
of flexibility for developers working from the repository.

Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
3 files changed