difficult_xml_unknown_elements test fails for Matrix

[mtelka]

The difficult_xml_unknown_elements test fails with this output:

/data/builds/oi-userland/components/library/opencolorio/OpenColorIO-2.4.0/tests/cpu/fileformats/FileFormatCTF_tests.cpp:1436:
FAILED: std::string::npos != StringUtils::Find(parts[i], ErrorOutputs[i])
        values were '18446744073709551615' and '18446744073709551615'

The difference is that the test expects this:

"(75): Unrecognized element 'Matrix' where its parent is 'LUT1D' (43): 'Matrix' not allowed in this element"

but it gets the following instead (please note 43 vs. 46):

"(75): Unrecognized element 'Matrix' where its parent is 'LUT1D' (46): 'Matrix' not allowed in this element"

And yes, the testing file contains the Matrix at line 46, not 43:

OpenColorIO/tests/data/files/difficult_test1_v1.ctf

Lines 40 to 48 in ed0c9ef

	<LUT1D id="4ed2af07-9319-430a-b18a-43368163c808" inBitDepth="32f" outBitDepth="32f"
	name='a multi-line
	name'>
	<Description>the n&#8211;dash description</Description>
	<Array dim="17 3">
	0.00000 0.00000 0.00000
	0.28358 2.8358E-1 0.28358
	0.38860 0.38860 0.38860