Add #define for ".bpf.fn."

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

src/cc/bpf_module.cc

@@ -76,7 +76,7 @@ using std::unique_ptr;
 using std::vector;
 using namespace llvm;
 
-const string BPFModule::FN_PREFIX = ".bpf.fn.";
+const string BPFModule::FN_PREFIX = BPF_FN_PREFIX;
 
 // Snooping class to remember the sections as the JIT creates them
 class MyMemoryManager : public SectionMemoryManager {

src/cc/codegen_llvm.cc

@@ -1166,7 +1166,7 @@ StatusTuple CodegenLLVM::visit_func_decl_stmt_node(FuncDeclStmtNode *n) {
   Function *fn = mod_->getFunction(n->id_->name_);
   if (fn) return mkstatus_(n, "Function %s already defined", n->id_->c_str());
   fn = Function::Create(fn_type, GlobalValue::ExternalLinkage, n->id_->name_, mod_);
-  fn->setSection(".bpf.fn." + n->id_->name_);
+  fn->setSection(BPF_FN_PREFIX + n->id_->name_);
 
   BasicBlock *label_entry = BasicBlock::Create(ctx(), "entry", fn);
   B.SetInsertPoint(label_entry);

src/cc/codegen_llvm.h

@@ -37,6 +37,8 @@ class StructType;
 class SwitchInst;
 }
 
+#define BPF_FN_PREFIX ".bpf.fn."
+
 namespace ebpf {
 namespace cc {