Commit 0c648bb644 for perl

commit 0c648bb644f23a739a11e8506f820be8aa887eaf
Author: Karl Williamson <khw@cpan.org>
Date:   Thu Sep 17 09:06:21 2026 -0600

    regcomp.c: Allow compilation for early Unicode versions

    If this code were ever to be compiled using an early Unicode version, it
    would fail.  Add an #ifdef to something that hasn't always existed.

diff --git a/regcomp.c b/regcomp.c
index 2bfda4571d..5a6d563161 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -7030,9 +7030,11 @@ S_regatom(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
                      * locale-problematic, they also have folds to above Latin1
                      * that aren't a problem.  Doing these now helps at
                      * runtime. */
-                    if (UNLIKELY(   ender == GREEK_CAPITAL_LETTER_MU
-                                 || ender == LATIN_CAPITAL_LETTER_SHARP_S))
-                    {
+                    if (   UNLIKELY(ender == GREEK_CAPITAL_LETTER_MU)
+#ifdef LATIN_CAPITAL_LETTER_SHARP_S
+                        || UNLIKELY(ender == LATIN_CAPITAL_LETTER_SHARP_S)
+#endif
+                    ) {
                         goto fold_anyway;
                     }