Author: Petr Skoda
MDL-32967 add diagnostic strings for missing Microsoft drivers for SQL Server
http://git.moodle.org/gw?p=moodle.git;a=commit;h=e98a486834fe476255110d498bd8c967ce89955d
http://github.com/moodle/moodle/commit/e98a486834fe476255110d498bd8c967ce89955d
+ 2.1 en [nativesqlsrvnodriver,core_install]
+ 2.1 en [nativesqlsrvnonwindows,core_install]