Add static-libgcc to clang toolchain flags.

Summary: Previous diff added `static-libgcc` to the gcc toolchain flags, but forgot to add it to the clang flags.

Test Plan: Run bpf tests with #ci:bpf-build .

Reviewers: zasgar, vihang

Reviewed By: zasgar, vihang

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

Differential Revision: https://phab.corp.pixielabs.ai/D12734

GitOrigin-RevId: fd71dedc4498ad9dc500c177a40c2e99fa692c2c

bazel/cc_toolchains/clang.bzl

@@ -95,6 +95,7 @@ def _clang_x86_64_gnu_with_options(suffix = "", enable_sanitizers = True, extra_
             "-fPIC",
         ],
         link_flags = [
+            "-static-libgcc",
             "-fuse-ld=lld",
             "-Wl,-no-as-needed",
             "-Wl,-z,relro,-z,now",