pgcrypto: Make header files stand alone

pgp.h used to require including mbuf.h and px.h first.  Include those in
pgp.h, so that it can be used without prerequisites.  Remove mbuf.h
inclusions in .c files where mbuf.h features are not used
directly.  (px.h was always used.)

contrib/pgcrypto/pgp-armor.c

@@ -32,7 +32,6 @@
 #include "postgres.h"
 
 #include "px.h"
-#include "mbuf.h"
 #include "pgp.h"
 
 /*

contrib/pgcrypto/pgp-cfb.c

@@ -31,7 +31,6 @@
 
 #include "postgres.h"
 
-#include "mbuf.h"
 #include "px.h"
 #include "pgp.h"
 

contrib/pgcrypto/pgp-compress.c

@@ -31,7 +31,6 @@
 
 #include "postgres.h"
 
-#include "mbuf.h"
 #include "px.h"
 #include "pgp.h"
 

contrib/pgcrypto/pgp-mpi-internal.c

@@ -33,7 +33,6 @@
 #include "imath.h"
 
 #include "px.h"
-#include "mbuf.h"
 #include "pgp.h"
 
 static mpz_t *

contrib/pgcrypto/pgp-mpi-openssl.c

@@ -33,7 +33,6 @@
 #include <openssl/bn.h>
 
 #include "px.h"
-#include "mbuf.h"
 #include "pgp.h"
 
 static BIGNUM *

contrib/pgcrypto/pgp-mpi.c

@@ -31,7 +31,6 @@
 #include "postgres.h"
 
 #include "px.h"
-#include "mbuf.h"
 #include "pgp.h"
 
 int

contrib/pgcrypto/pgp-pubdec.c

@@ -31,7 +31,6 @@
 #include "postgres.h"
 
 #include "px.h"
-#include "mbuf.h"
 #include "pgp.h"
 
 /*

contrib/pgcrypto/pgp-pubenc.c

@@ -31,7 +31,6 @@
 #include "postgres.h"
 
 #include "px.h"
-#include "mbuf.h"
 #include "pgp.h"
 
 /*

contrib/pgcrypto/pgp-s2k.c

@@ -32,7 +32,6 @@
 #include "postgres.h"
 
 #include "px.h"
-#include "mbuf.h"
 #include "pgp.h"
 
 static int

contrib/pgcrypto/pgp.c

@@ -32,7 +32,6 @@
 #include "postgres.h"
 
 #include "px.h"
-#include "mbuf.h"
 #include "pgp.h"
 
 /*

contrib/pgcrypto/pgp.h

@@ -29,6 +29,9 @@
  * contrib/pgcrypto/pgp.h
  */
 
+#include "mbuf.h"
+#include "px.h"
+
 enum PGP_S2K_TYPE
 {
 	PGP_S2K_SIMPLE = 0,