Ext. functions now use the same shm handler and it counts as another subprocess.
This way we remove the ambiguity when a DLB process wants to call DROM
specific features.

Fix issue with shadowing in older compilers

Fix #64

Fix #69

Setting LB_ARGS="..." was causing non-defined options to be empty
instead of parse the default value

Do a true reset in shmem_cpuinfo by acquiring all owned CPUs and
lending the rest. The previous logic was wrong, a simple AcquireCpuMask
is not enoutgh.

In polling mode, DLB must always enable the CPU and let the runtime decide
whether there will be CPU sharing by calling checkCPUAvailability
Also, fix needed in shmem_cpuinfo__is_cpu_available to support the current
mechanism in AcquireCpu

HWLOC_LIBDIR needs to be exported without link flags. For that reason,
a bit of refactoring has been needed in ax_hwloc

Several flags are needed, and CFLAGS cannot be shared since there
are some incompatible flags

Now all policy functions must return an integer. If the function is not defined,
a new error value DLB_ERR_NOPOL is returned.