This is the only dependency that accepts an ereg()able pattern. The pattern
will be matched against the php_uname() output parsed by OS_Guess
As with all dependency validation, true is returned on success, PEAR_Error on failure
for required dependencies (and the arch dependency is required). If the
options are specified, an array containing the error message will be returned instead.
Contents of the dependency, as parsed from xml.
throws no exceptions thrown
This function can not be called statically.