Added a parameter 'failOnDataTypeUnsupported' to getDbInfo (that defaults to TRUE...

Added a parameter 'failOnDataTypeUnsupported' to getDbInfo (that defaults to TRUE keeping current functional behavior intact)), that will allow the user to override whether a call to getDbInfo() should fail immediately if a data type request reports back that it is unsupported/unavailable
fixed issues with wxDb::DBMS() that were not correctly detecting MySQL databases using MySQL v4.  also removed erroneous/duplicated code in this function that looked like a result of a bad merge at some point

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@24600 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775