fix type of S_restore_magic and S_unwind_handler_stack

SAVEDESTRUCTOR_X needs a function of type 'void (pTHX_ void *)' exactly.

Should fix this ASan error:

    scope.c:1543:13: runtime error: call to function S_restore_magic through pointer to incorrect function type 'void (*)(struct interpreter *, void *)'
    scope.c:1543:13: runtime error: call to function S_unwind_handler_stack through pointer to incorrect function type 'void (*)(struct interpreter *, void *)'

Author: mauke

embed.fnc

@@ -4825,13 +4825,13 @@ S	|SV *	|magic_methcall1|NN SV *sv				\
 S	|int	|magic_methpack |NN SV *sv				\
 				|NN const MAGIC *mg			\
 				|NN SV *meth
-S	|void	|restore_magic	|NULLOK const void *p
+S	|void	|restore_magic	|NULLOK void *p
 S	|void	|save_magic_flags					\
 				|SSize_t mgs_ix 			\
 				|NN SV *sv				\
 				|U32 flags
 S	|void	|unwind_handler_stack					\
-				|NULLOK const void *p
+				|NULLOK void *p
 #endif
 #if defined(PERL_IN_MG_C) || defined(PERL_IN_PP_C)
 Tp	|bool	|translate_substr_offsets				\

mg.c

@@ -3824,7 +3824,7 @@ Perl_perly_sighandler(int sig, Siginfo_t *sip PERL_UNUSED_DECL,
 
 
 static void
-S_restore_magic(pTHX_ const void *p)
+S_restore_magic(pTHX_ void *p)
 {
     MGS* const mgs = SSPTR(PTR2IV(p), MGS*);
     SV* const sv = mgs->mgs_sv;
@@ -3881,7 +3881,7 @@ S_restore_magic(pTHX_ const void *p)
  * skipped over. */
 
 static void
-S_unwind_handler_stack(pTHX_ const void *p)
+S_unwind_handler_stack(pTHX_ void *p)
 {
     PERL_UNUSED_ARG(p);