Rm Perl_sv_pvutf8() from mathoms

This function can be converted to call plain sv_pvutf8  without changing
its behavior.  I verified this by eyeballing its implementation in
mathoms.c and comparing that with what happens with just the plain
macro.

That means embed.fnc can be changed to generate the Perl_ form
automatically, and the mathoms function can be removed.

Author: khwilliamson

embed.fnc

@@ -3337,7 +3337,7 @@ Adp	|char * |sv_pvn_force_flags					\
 CRdmp	|char * |sv_2pv_nolen	|NN SV *sv
 Admp	|char * |sv_2pvutf8	|NN SV *sv				\
 				|NULLOK STRLEN * const lp
-CMRbdp	|char * |sv_pvutf8	|NN SV *sv
+CRdmp	|char * |sv_pvutf8	|NN SV *sv
 Adp	|char * |sv_2pvutf8_flags					\
 				|NN SV *sv				\
 				|NULLOK STRLEN * const lp		\

embed.h

@@ -2319,6 +2319,7 @@
 #   define Perl_sv_insert(mTHX,a,b,c,d,e)       sv_insert(a,b,c,d,e)
 #   define Perl_sv_mortalcopy(mTHX,a)           sv_mortalcopy(a)
 #   define Perl_sv_pvn_force(mTHX,a,b)          sv_pvn_force(a,b)
+#   define Perl_sv_pvutf8(mTHX,a)               sv_pvutf8(a)
 #   define Perl_sv_setsv(mTHX,a,b)              sv_setsv(a,b)
 #   define Perl_sv_taint(mTHX,a)                sv_taint(a)
 #   define Perl_sv_unref(mTHX,a)                sv_unref(a)
@@ -2379,6 +2380,7 @@
 #   define Perl_sv_insert                       sv_insert
 #   define Perl_sv_mortalcopy                   sv_mortalcopy
 #   define Perl_sv_pvn_force                    sv_pvn_force
+#   define Perl_sv_pvutf8                       sv_pvutf8
 #   define Perl_sv_setsv                        sv_setsv
 #   define Perl_sv_taint                        sv_taint
 #   define Perl_sv_unref                        sv_unref

mathoms.c

@@ -119,15 +119,6 @@ Perl_sv_pvbyte(pTHX_ SV *sv)
     return sv_pv(sv);
 }
 
-char *
-Perl_sv_pvutf8(pTHX_ SV *sv)
-{
-    PERL_ARGS_ASSERT_SV_PVUTF8;
-
-    sv_utf8_upgrade(sv);
-    return sv_pv(sv);
-}
-
 #if defined(HUGE_VAL) || (defined(USE_LONG_DOUBLE) && defined(HUGE_VALL))
 /*
  * This hack is to force load of "huge" support from libm.a