Bug#17280 mysqltest, --echo sometimes does not expand $variables

- Evaluate all variables in the text before printing it to result file


client/mysqltest.c:
  Update echo command to vvaluate all variables in the string before printing, allow
  for variable names to be escaped using \
mysql-test/r/mysqltest.result:
  Update results for echo
mysql-test/t/mysqltest.test:
  Add more advanced tests for echo of strings with several variables 
  and/or text plus variables. Also test that variables can be escaped

mysql-test/r/mysqltest.result

@@ -201,8 +201,14 @@ source database
 - world''s most
 -- popular open
 # source database
-'$message'
-"$message"
+'# MySQL: The
+- world''s most
+-- popular open
+# source database'
+"# MySQL: The
+- world''s most
+-- popular open
+# source database"
 hej
 hej 
 hej
@@ -222,6 +228,15 @@ mysqltest: At line 1: Missing arguments to let
 mysqltest: At line 1: Missing variable name in let
 mysqltest: At line 1: Variable name in =hi does not start with '$'
 mysqltest: At line 1: Missing assignment operator in let
+# Execute: --echo # <whatever> success: $success
+# <whatever> success: 1
+# Execute: echo # <whatever> success: $success ;
+# <whatever> success: 1 
+# The next two variants work fine and expand the content of $success
+# Execute: --echo $success
+1
+# Execute: echo $success ;
+1 
 mysqltest: At line 1: Missing file name in source
 mysqltest: At line 1: Could not open file ./non_existingFile
 mysqltest: In included file "./var/tmp/recursive.sql": At line 1: Source directives are nesting too deep

mysql-test/t/mysqltest.test

@@ -539,6 +539,19 @@ echo $novar1;
 --error 1
 --exec echo "let hi;" | $MYSQL_TEST  2>&1
 
+# More advanced test for bug#17280
+let $success= 1;
+--echo # Execute: --echo # <whatever> success: \$success
+--echo # <whatever> success: $success
+--echo # Execute: echo # <whatever> success: \$success ;
+echo # <whatever> success: $success ;
+
+--echo # The next two variants work fine and expand the content of \$success
+--echo # Execute: --echo \$success
+--echo $success
+--echo # Execute: echo \$success ;
+echo $success ;
+
 # ----------------------------------------------------------------------------
 # Test to assign let from query
 # let $<var_name>=`<query>`;