Change "exec rm" to "remove_file"

mysql-test/t/sp.test:
  Change "exec rm" to "remove_file"
  Change two "remove file if exists" to "check that file not exist"

mysql-test/include/have_outfile.inc

 -- require r/have_outfile.require
 disable_query_log;
 select load_file(concat(@tmpdir,"/outfile.test"));
---exec rm $MYSQLTEST_VARDIR/tmp/outfile.test
+--remove_file $MYSQLTEST_VARDIR/tmp/outfile.test
 enable_query_log;

mysql-test/t/sp.test

@@ -705,9 +705,11 @@ begin
   insert into test.t1 values (concat(x, "2"), y+2);
 end|
 
---system rm -f $MYSQLTEST_VARDIR/tmp/spout
+# Check that file does not exists
+--error 1
+--file_exists $MYSQLTEST_VARDIR/tmp/spout
 call into_outfile("ofile", 1)|
---system rm -f $MYSQLTEST_VARDIR/tmp/spout
+--remove_file $MYSQLTEST_VARDIR/tmp/spout
 delete from t1|
 drop procedure into_outfile|
 
@@ -722,9 +724,11 @@ begin
   insert into test.t1 values (concat(x, "2"), y+2);
 end|
 
---system rm -f $MYSQLTEST_VARDIR/tmp/spdump
+# Check that file does not exists
+--error 1
+--file_exists $MYSQLTEST_VARDIR/tmp/spdump
 call into_dumpfile("dfile", 1)|
---system rm -f $MYSQLTEST_VARDIR/tmp/spdump
+--remove_file $MYSQLTEST_VARDIR/tmp/spdump
 delete from t1|
 drop procedure into_dumpfile|