Move binpac code into the main Zeek repository

This is based on commit 48f75b5f6415fe9d597e3e991cec635b1bc400dc from
the binpac repository.

tools/binpac/src/pac_func.h

@@ -0,0 +1,65 @@
+#ifndef pac_func_h
+#define pac_func_h
+
+#include "pac_analyzer.h"
+#include "pac_decl.h"
+
+class Function : public Object {
+public:
+    Function(ID* id, Type* type, ParamList* params);
+    ~Function();
+
+    ID* id() const { return id_; }
+
+    AnalyzerDecl* analyzer_decl() const { return analyzer_decl_; }
+    void set_analyzer_decl(AnalyzerDecl* decl) { analyzer_decl_ = decl; }
+
+    Expr* expr() const { return expr_; }
+    void set_expr(Expr* expr) { expr_ = expr; }
+
+    EmbeddedCode* code() const { return code_; }
+    void set_code(EmbeddedCode* code) { code_ = code; }
+
+    void Prepare(Env* env);
+    void GenForwardDeclaration(Output* out_h);
+    void GenCode(Output* out_h, Output* out_cc);
+
+private:
+    Env* env_;
+
+    ID* id_;
+    Type* type_;
+    ParamList* params_;
+
+    AnalyzerDecl* analyzer_decl_;
+
+    Expr* expr_;
+    EmbeddedCode* code_;
+};
+
+class FuncDecl : public Decl {
+public:
+    FuncDecl(Function* function);
+    ~FuncDecl() override;
+
+    Function* function() const { return function_; }
+
+    void Prepare() override;
+    void GenForwardDeclaration(Output* out_h) override;
+    void GenCode(Output* out_h, Output* out_cc) override;
+
+private:
+    Function* function_;
+};
+
+class AnalyzerFunction : public AnalyzerElement {
+public:
+    AnalyzerFunction(Function* function);
+
+    Function* function() const { return function_; }
+
+private:
+    Function* function_;
+};
+
+#endif // pac_func_h