Case issue in Os.isOs(). Creates hard to identify maven profile activation failures (Patch attached)

My os.name is Linux. If I use <name>Linux</name> in my pom.xml, the profile doesn't get activated. If I use <name>linux.. it is.

Problem probably created because the Os class mixes instance and class methods. Calls to instance methods are correctly handled (fields are case-lowered when set), while class ones are not (parameters are not case-lowered). Wonder if the issue was fixed in Ant...

I haven't tested the patch yet, having problems making maven reuse the fixed plexus-utils, but I believe this should work.