Fix typos in comments.

src/backend/access/brin/brin_inclusion.c

@@ -431,7 +431,7 @@ brin_inclusion_consistent(PG_FUNCTION_ARGS)
 			 * It is straightforward to support the equality strategies with
 			 * the contains operator.  Generally, inequality strategies do not
 			 * make much sense for the types which will be used with the
-			 * inclusion BRIN family of opclasses, but is is possible to
+			 * inclusion BRIN family of opclasses, but is possible to
 			 * implement them with logical negation of the left-of and
 			 * right-of operators.
 			 *

src/timezone/localtime.c

@@ -489,7 +489,7 @@ tzloadbody(char const * name, char *canonname, struct state * sp, bool doextend,
 	}
 
 	/*
-	 * If type 0 is is unused in transitions, it's the type to use for early
+	 * If type 0 is unused in transitions, it's the type to use for early
 	 * times.
 	 */
 	for (i = 0; i < sp->timecnt; ++i)