Remove unnecessary definition of CancelRequested in bin/scripts/

This variable is now part of the refactored code for query cancellation
in fe_utils.  This fixes an oversight in commit a4fd3aa7.  While on it,
improve some header includes in bin/scripts/.

Author: Michael Paquier
Reviewed-by: Fabien Coelho
Discussion: https://postgr.es/m/20191203101625.GF1634@paquier.xyz

src/bin/scripts/clusterdb.c

@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 #include "common.h"
 #include "common/logging.h"
+#include "fe_utils/cancel.h"
 #include "fe_utils/simple_list.h"
 #include "fe_utils/string_utils.h"
 

src/bin/scripts/common.c

@@ -19,6 +19,7 @@
 
 #include "common.h"
 #include "common/logging.h"
+#include "fe_utils/cancel.h"
 #include "fe_utils/connect.h"
 #include "fe_utils/string_utils.h"
 

src/bin/scripts/common.h

@@ -10,7 +10,6 @@
 #define COMMON_H
 
 #include "common/username.h"
-#include "fe_utils/cancel.h"
 #include "getopt_long.h"		/* pgrminclude ignore */
 #include "libpq-fe.h"
 #include "pqexpbuffer.h"		/* pgrminclude ignore */
@@ -22,8 +21,6 @@ enum trivalue
 	TRI_YES
 };
 
-extern bool CancelRequested;
-
 typedef void (*help_handler) (const char *progname);
 
 extern void handle_help_version_opts(int argc, char *argv[],

src/bin/scripts/reindexdb.c

@@ -14,6 +14,7 @@
 #include "catalog/pg_class_d.h"
 #include "common.h"
 #include "common/logging.h"
+#include "fe_utils/cancel.h"
 #include "fe_utils/connect.h"
 #include "fe_utils/simple_list.h"
 #include "fe_utils/string_utils.h"

src/bin/scripts/scripts_parallel.c

@@ -24,6 +24,7 @@
 
 #include "common.h"
 #include "common/logging.h"
+#include "fe_utils/cancel.h"
 #include "scripts_parallel.h"
 
 static void init_slot(ParallelSlot *slot, PGconn *conn);

src/bin/scripts/vacuumdb.c

@@ -16,6 +16,7 @@
 
 #include "common.h"
 #include "common/logging.h"
+#include "fe_utils/cancel.h"
 #include "fe_utils/connect.h"
 #include "fe_utils/simple_list.h"
 #include "fe_utils/string_utils.h"