Fix bug#56547 mysql client interprets commands in comments

The problem was not caused by a change in the client,
rather by the tests using the Windows built-in "echo"
and not the one built by MySQL.
This again happened because the binary was missing in the package,
caused by the wrong macro being used to build it in "cmake".

client/CMakeLists.txt

@@ -64,7 +64,10 @@ MYSQL_ADD_EXECUTABLE(mysqlslap mysqlslap.c)
 SET_SOURCE_FILES_PROPERTIES(mysqlslap.c PROPERTIES COMPILE_FLAGS "-DTHREADS")
 TARGET_LINK_LIBRARIES(mysqlslap mysqlclient)
 
-ADD_EXECUTABLE(echo echo.c)
+# "WIN32" also covers 64 bit. "echo" is used in some files below "mysql-test/".
+IF(WIN32)
+  MYSQL_ADD_EXECUTABLE(echo echo.c)
+ENDIF(WIN32)
 
 SET_TARGET_PROPERTIES (mysqlcheck mysqldump mysqlimport mysql_upgrade mysqlshow mysqlslap 
 PROPERTIES HAS_CXX TRUE)