Fix header file inclusion for PG_PRINTF_ATTRIBUTE in mapred

Commit 8e60838c22735fcacabc125170fc1d removed PG_PRINTF_ATTRIBUTE
from pg_config_manual.h, which exposed the fact that gpmapreduce
was erroneously including that header instead of the correct one.
Instead include postgres_fe.h for now, as gpmapreduce is client
side tool and not a separated extension, to fix compilation.
Reviewed-by: NAsim R P <apraveen@pivotal.io>

gpAux/extensions/gpmapreduce/include/mapred.h

 #ifndef MAPRED_H
 #define MAPRED_H
 
+#include <postgres_fe.h>
+
 #ifndef YAML_H
 #include <yaml.h>
 #endif

gpAux/extensions/gpmapreduce/src/mapred.c

@@ -6,7 +6,6 @@
 #include <stdarg.h>
 #include <unistd.h>     /* for file "access" test */
 #include <errno.h>
-#include "pg_config_manual.h"
 
 #define scalarfree(x)							\
 	do {										\

gpAux/extensions/gpmapreduce/src/parse.c

@@ -7,7 +7,6 @@
 #include <yaml.h>
 
 #include <stdarg.h>
-#include "pg_config_manual.h"
 
 int mapred_parse_error(mapred_parser_t *parser, char *fmt, ...)
 	__attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 3)));