doc: Update redirecting links

Update links that resulted in redirects.  Most are changes from http to
https, but there are also some other minor edits.  (There are still some
redirects where the target URL looks less elegant than the one we
currently have.  I have left those as is.)

src/backend/lib/bipartite_match.c

@@ -5,7 +5,7 @@
  *
  * This implementation is based on pseudocode found at:
  *
- * http://en.wikipedia.org/w/index.php?title=Hopcroft%E2%80%93Karp_algorithm&oldid=593898016
+ * https://en.wikipedia.org/w/index.php?title=Hopcroft%E2%80%93Karp_algorithm&oldid=593898016
  *
  * Copyright (c) 2015-2018, PostgreSQL Global Development Group
  *

src/backend/utils/adt/numeric.c

@@ -8353,7 +8353,7 @@ power_var_int(const NumericVar *base, int exp, NumericVar *result, int rscale)
 			 * While 0 ^ 0 can be either 1 or indeterminate (error), we treat
 			 * it as 1 because most programming languages do this. SQL:2003
 			 * also requires a return value of 1.
-			 * http://en.wikipedia.org/wiki/Exponentiation#Zero_to_the_zero_power
+			 * https://en.wikipedia.org/wiki/Exponentiation#Zero_to_the_zero_power
 			 */
 			set_var_from_var(&const_one, result);
 			result->dscale = rscale;	/* no need to round */

src/bin/pgbench/pgbench.c

@@ -763,7 +763,7 @@ getGaussianRand(TState *thread, int64 min, int64 max, double parameter)
 		 * pg_erand48 generates [0,1), but for the basic version of the
 		 * Box-Muller transform the two uniformly distributed random numbers
 		 * are expected in (0, 1] (see
-		 * http://en.wikipedia.org/wiki/Box_muller)
+		 * https://en.wikipedia.org/wiki/Box-Muller_transform)
 		 */
 		double		rand1 = 1.0 - pg_erand48(thread->random_state);
 		double		rand2 = 1.0 - pg_erand48(thread->random_state);