Add forgotten CHECK_FOR_INTERRUPT calls in pgcrypto's crypt()

Both Blowfish and DES implementations of crypt() can take arbitrarily
long time, depending on the number of rounds specified by the caller;
make sure they can be interrupted.

Author: Andreas Karlsson
Reviewer: Jeff Janes

Backpatch to 9.1.

Author: alvherre

contrib/pgcrypto/crypt-blowfish.c

@@ -33,6 +33,7 @@
  */
 
 #include "postgres.h"
+#include "miscadmin.h"
 
 #include "px-crypt.h"
 #include "px.h"
@@ -670,6 +671,8 @@ _crypt_blowfish_rn(const char *key, const char *setting,
 
 	do
 	{
+		CHECK_FOR_INTERRUPTS();
+
 		data.ctx.P[0] ^= data.expanded_key[0];
 		data.ctx.P[1] ^= data.expanded_key[1];
 		data.ctx.P[2] ^= data.expanded_key[2];

contrib/pgcrypto/crypt-des.c

@@ -61,6 +61,7 @@
  */
 
 #include "postgres.h"
+#include "miscadmin.h"
 
 #include "px-crypt.h"
 
@@ -540,6 +541,8 @@ do_des(uint32 l_in, uint32 r_in, uint32 *l_out, uint32 *r_out, int count)
 
 	while (count--)
 	{
+		CHECK_FOR_INTERRUPTS();
+
 		/*
 		 * Do each round.
 		 */