sys/embunit: revised header include guards.

sys/embunit/ColorTextColors.h

sys/include/embUnit.h

sys/include/embUnit/AssertImpl.h

sys/include/embUnit/ColorOutputter.h

sys/include/embUnit/ColorTextOutputter.h

sys/include/embUnit/CompilerOutputter.h

sys/include/embUnit/HelperMacro.h

sys/include/embUnit/Outputter.h

sys/include/embUnit/RepeatedTest.h

sys/include/embUnit/Test.h

sys/include/embUnit/TestCaller.h

sys/include/embUnit/TestCase.h

sys/include/embUnit/TestListener.h

sys/include/embUnit/TestResult.h

sys/include/embUnit/TestRunner.h

sys/include/embUnit/TestSuite.h

sys/include/embUnit/TextOutputter.h

sys/include/embUnit/TextUIRunner.h

sys/include/embUnit/XMLOutputter.h

sys/include/embUnit/embUnit.h