[Indic] Don't move virama with left matra

[Indic] Don't move virama with left matra

This is important for the Sinhala U+0DDA split matra since it decomposes
to U+0DD9,U+0DCA where U+0DD9 is a left matra and U+0DCA is the virama.
We don't want to move the virama with the left matra.
TEST: U+0D9A,U+0DDA

Note that we were already doing this in the Uniscribe bug compatibility
mode.  We now do it all the time.