bpf: Fix build caching for objects with options
bpf: Fix build caching for objects with options

Previously, the build targets for the bpf_*.o files which need testing
with multiple options were not creating the actual object file, so
every time someone builds the bpf/ directory, it must recompile each of
the files inside even if nothing in the code changed.

Fix this issue by actually generating the file with no options while
making these targets.

Signed-off-by: Joe Stringer <16a9a54ddf4259952e3c118c763138e83693d7fd@covalent.io>

tklauser/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,eloycoto/cilium,michi-covalent/cilium,cilium-team/cilium,scanf/cilium,tgraf/cilium,scanf/cilium,michi-covalent/cilium,tklauser/cilium,cilium-team/cilium,eloycoto/cilium,eloycoto/cilium,michi-covalent/cilium,scanf/cilium,tklauser/cilium,eloycoto/cilium,tgraf/cilium,eloycoto/cilium,scanf/cilium,scanf/cilium,michi-covalent/cilium,tklauser/cilium,cilium/cilium,tgraf/cilium,tgraf/cilium,tklauser/cilium,eloycoto/cilium,scanf/cilium,eloycoto/cilium,cilium/cilium,scanf/cilium,tgraf/cilium,tgraf/cilium