libelf: Prefer libelf from toolchain except for darwin builds
libelf: Prefer libelf from toolchain except for darwin builds

With libelf packaging fixed in gcc recipe in OE-lite/core, we now have
multiple libelf providers. Let's use the one from gcc recipe, except
for darwin builds.

Signed-off-by: Esben Haabendal <c5ba3f1141bb30a64dd6c7e6726a53a85adc9442@prevas.dk>

moths/base,hundeboll/base,esben/base,oe-lite/base,hundeboll/base,hundeboll/base,kimrhh/base,kimrhh/base,moths/base,hundeboll/base,diorcety/oe-lite-base,oe-lite/base,oe-lite/base,esben/base,sknsean/base,moths/base,moths/base,oe-lite/base,esben/base,esben/base,oe-lite/base,sknsean/base,kimrhh/base,hundeboll/base,oe-lite/base,hundeboll/base,sknsean/base,kimrhh/base,sknsean/base,esben/base,esben/base,kimrhh/base,kimrhh/base,moths/base,sknsean/base,diorcety/oe-lite-base,moths/base,sknsean/base