Demo tasks only, with the aim of improving test coverage:
+ Split out the code that uses a mutex from an interrupt from GenQTest.c and add to new common demo task IntSemTest.c.

git-svn-id: http://svn.code.sf.net/p/freertos/code/trunk@2303 1d2547de-c912-0410-9cb9-b8ca96c0e9e2