Invalid Rendering of Bengali Yaphala and Kannada kaphala when occur with reph

Bengali 0x09B0, 0x200D, 0x09cd, 0x09af র‍্য ­and Kannada 0x0CB0, 0x200D, 0x0ccd, 0x0c95 ರ‍್ಕ combinations are not rendering properly in qt/harfbuzz

presently harfbuzz break string (0x09B0, 0x200D, 0x09cd, 0x09af) into 3 syllables 1) 0x09B0, 0x200D, 2) 09cd 3) 09af results in invalid rendering, actually this should form a single syllable

see http://www.unicode.org/faq/indic.html#15
same case is application for Kannada as well

I have attached patch for fixing it, it resolves the problem, but somehow cursor is not moving at the end of this syllable might be need some more line in patch