fix integer overflow in S_study_chunk().

Don't increment delta if it's "infinity" (SSize_t_MAX)
Found by -fsanitize=undefined:

regcomp.c:4999:11: runtime error: signed integer overflow: 9223372036854775807 + 1 cannot be represented in type 'ssize_t' (aka 'long')

1 files changed, 2 insertions, 1 deletions

diff --git a/regcomp.c b/regcomp.c
index 4f5753a27b..b11047fe9a 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -5022,7 +5022,8 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
 		flags &= ~SCF_DO_STCLASS;
             }
 	    min++;
-	    delta++;    /* Because of the 2 char string cr-lf */
+            if (delta != SSize_t_MAX)
+                delta++;    /* Because of the 2 char string cr-lf */
             if (flags & SCF_DO_SUBSTR) {
                 /* Cannot expect anything... */
                 scan_commit(pRExC_state, data, minlenp, is_inf);