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

Begnali Combination 0x09B0, 0x200D, 0x09cd, 0x09af, র‍্য
kannada Combination 0x0CB0, 0x200D, 0x0ccd, 0x0c95 ರ‍್ಕ

not rendering properly, this is special exception in Bengali and Kannada script, see http://www.unicode.org/faq/indic.html#15

presently qt/harfbuzz breaking above string (0x09B0, 0x200D, 0x09cd, 0x09af) in syllbale 1) 0x09B0, 0x200D, 2) 0x09cd (invalid) 3) 0x09af affect in invalid rendering of sequence, same for kannada as well

actually this should be consider as a single syllable, will make its rendering as expected

i have created patch agaisnt 4.6.3 but same application to 4.7.0 as well, after applying patch rendering happen properly but somehow in kwrite cursor is not coming at the end of this syllable, so please check that, i will update if any update from my side