Remove obsolete cast

The upstream timezone code uses a bool variable as an array subscript.
Back when PostgreSQL's bool was char, this would have caused a warning
from gcc -Wchar-subscripts, which is included in -Wall.  But this has
been obsolete since probably commit d26a810ebf, but certainly since
bool is now the C standard bool.  So we can remove this deviation from
the upstream code, to make future code merges simpler.

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/9ad2749f-77ab-4ecb-a321-1ca915480b05%40eisentraut.org

src/timezone/localtime.c

@@ -905,7 +905,7 @@ transtime(const int year, const struct rule *const rulep,
 			for (i = 1; i < rulep->r_week; ++i)
 			{
 				if (d + DAYSPERWEEK >=
-					mon_lengths[(int) leapyear][rulep->r_mon - 1])
+					mon_lengths[leapyear][rulep->r_mon - 1])
 					break;
 				d += DAYSPERWEEK;
 			}
@@ -915,7 +915,7 @@ transtime(const int year, const struct rule *const rulep,
 			 */
 			value = d * SECSPERDAY;
 			for (i = 0; i < rulep->r_mon - 1; ++i)
-				value += mon_lengths[(int) leapyear][i] * SECSPERDAY;
+				value += mon_lengths[leapyear][i] * SECSPERDAY;
 			break;
 	}