Revert "plperl: Fix breakage of c89f409749 in back branches."

This reverts commits d81cac47a et al.  We shouldn't need that
hack after the preceding commits.

Discussion: https://postgr.es/m/20220131015130.shn6wr2fzuymerf6@alap3.anarazel.de

src/pl/plperl/plperl.c

@@ -298,11 +298,11 @@ static char *strip_trailing_ws(const char *msg);
 static OP  *pp_require_safe(pTHX);
 static void activate_interpreter(plperl_interp_desc *interp_desc);
 
-#if defined(WIN32) && PERL_VERSION < 28
+#if defined(WIN32) && PERL_VERSION_LT(5, 28, 0)
 static char *setlocale_perl(int category, char *locale);
 #else
 #define setlocale_perl(a,b)  Perl_setlocale(a,b)
-#endif							/* defined(WIN32) && PERL_VERSION < 28 */
+#endif							/* defined(WIN32) && PERL_VERSION_LT(5, 28, 0) */
 
 /*
  * Decrement the refcount of the given SV within the active Perl interpreter
@@ -4135,7 +4135,7 @@ plperl_inline_callback(void *arg)
  *
  * Starting in 5.28, perl exposes Perl_setlocale to do so.
  */
-#if defined(WIN32) && PERL_VERSION < 28
+#if defined(WIN32) && PERL_VERSION_LT(5, 28, 0)
 static char *
 setlocale_perl(int category, char *locale)
 {
@@ -4203,4 +4203,4 @@ setlocale_perl(int category, char *locale)
 
 	return RETVAL;
 }
-#endif							/* defined(WIN32) && PERL_VERSION < 28 */
+#endif							/* defined(WIN32) && PERL_VERSION_LT(5, 28, 0) */