Set cpu=v1 explicitly

Upstream patch
  llvm/llvm-project#107008
makes cpu=v3 as the default. Previously cpu=v1 as the default for bcc.
Let us mark cpu=v1 explicitly for bcc for now to keep it backword
compatible.

Author: Yonghong Song

src/cc/bpf_module.cc

@@ -574,6 +574,7 @@ int BPFModule::finalize() {
   builder.setMCJITMemoryManager(
       ebpf::make_unique<MyMemoryManager>(sections_p, &*prog_func_info_));
   builder.setMArch("bpf");
+  builder.setMCPU("v1");
 #if LLVM_VERSION_MAJOR <= 11
   builder.setUseOrcMCJITReplacement(false);
 #endif