[bpftrace] Disable pulling in of libpcap.

Summary: If `libpcap-dev` is installed on a machine it causes the bpftrace build to fail. This diff prevents bpftrace from pulling in libpcap.

Test Plan: Installed libpcap-dev and tested that bpftrace still builds

Reviewers: #stirling, jps, zasgar

Reviewed By: #stirling, jps

Signed-off-by: James Bartlett <jamesbartlett@pixielabs.ai>

Differential Revision: https://phab.corp.pixielabs.ai/D12482

GitOrigin-RevId: 8b72dc1f8b2e90cf8db0b4073834a1d5bf16acd4

bazel/external/bpftrace.BUILD

@@ -41,6 +41,7 @@ cmake(
         "ENABLE_BPFTRACE_EXE": "OFF",
         "ENABLE_LIBDW": "OFF",
         "ENABLE_MAN": "OFF",
+        "ENABLE_SKB_OUTPUT": "OFF",
 
         # Provide paths to dependent binaries: libbpf, bcc and libcereal.
         # Notice that bcc and libceral are in the bazel deps below as well.