Allow defining extra targets to build kernel builtin libs for
Allow defining extra targets to build kernel builtin libs for

Controllable via EXTRA_OCL_TARGETS (a space separated list).

franz/pocl,Oblomov/pocl,Oblomov/pocl,pocl/pocl,Oblomov/pocl,pocl/pocl,pocl/pocl,franz/pocl,pocl/pocl,franz/pocl,Oblomov/pocl,Oblomov/pocl,franz/pocl,pocl/pocl,franz/pocl