Add `const` before `struct mrb_irep` in `mruby-bin-debugger` gem.

mrbgems/mruby-bin-debugger/tools/mrdb/apibreak.c

@@ -84,7 +84,7 @@ free_breakpoint(mrb_state *mrb, mrb_debug_breakpoint *bp)
 }
 
 static uint16_t
-check_file_lineno(mrb_state *mrb, struct mrb_irep *irep, const char *file, uint16_t lineno)
+check_file_lineno(mrb_state *mrb, const struct mrb_irep *irep, const char *file, uint16_t lineno)
 {
   mrb_irep_debug_info_file *info_file;
   uint16_t result = 0;
@@ -428,7 +428,7 @@ mrb_debug_disable_break_all(mrb_state *mrb, mrb_debug_context *dbg)
 }
 
 static mrb_bool
-check_start_pc_for_line(mrb_state *mrb, mrb_irep *irep, const mrb_code *pc, uint16_t line)
+check_start_pc_for_line(mrb_state *mrb, const mrb_irep *irep, const mrb_code *pc, uint16_t line)
 {
   if (pc > irep->iseq) {
     if (line == mrb_debug_get_line(mrb, irep, pc - irep->iseq - 1)) {

mrbgems/mruby-bin-debugger/tools/mrdb/apiprint.c

@@ -33,7 +33,7 @@ mrdb_check_syntax(mrb_state *mrb, mrb_debug_context *dbg, const char *expr, size
 mrb_value
 mrb_debug_eval(mrb_state *mrb, mrb_debug_context *dbg, const char *expr, size_t len, mrb_bool *exc, int direct_eval)
 {
-  void (*tmp)(struct mrb_state *, struct mrb_irep *, const mrb_code *, mrb_value *);
+  void (*tmp)(struct mrb_state *, const struct mrb_irep *, const mrb_code *, mrb_value *);
   mrb_value ruby_code;
   mrb_value s;
   mrb_value v;

mrbgems/mruby-bin-debugger/tools/mrdb/mrdb.c

@@ -504,7 +504,7 @@ get_and_parse_command(mrb_state *mrb, mrdb_state *mrdb)
 }
 
 static int32_t
-check_method_breakpoint(mrb_state *mrb, mrb_irep *irep, const mrb_code *pc, mrb_value *regs)
+check_method_breakpoint(mrb_state *mrb, const mrb_irep *irep, const mrb_code *pc, mrb_value *regs)
 {
   struct RClass* c;
   mrb_sym sym;

mrbgems/mruby-bin-debugger/tools/mrdb/mrdb.h

@@ -103,8 +103,8 @@ typedef struct mrb_debug_breakpoint {
 } mrb_debug_breakpoint;
 
 typedef struct mrb_debug_context {
-  struct mrb_irep *root_irep;
-  struct mrb_irep *irep;
+  const struct mrb_irep *root_irep;
+  const struct mrb_irep *irep;
   const mrb_code *pc;
   mrb_value *regs;