Update waveflag.c from upstream.
Update waveflag.c from upstream.

Also, we call this a bit differently than upstream so have a slight change.
Add comment to highlight this more.

the

googlefonts/noto-emoji,radiocane/noto-emoji,mxalbert1996/emojione-android,radiocane/noto-emoji,julroy67/noto-emoji,julroy67/noto-emoji,googlei18n/noto-emoji,googlefonts/noto-emoji,dougfelt/noto-emoji,googlei18n/noto-emoji,googlefonts/noto-emoji,googlei18n/noto-emoji,moyogo/noto-emoji,dougfelt/noto-emoji,dougfelt/noto-emoji,moyogo/noto-emoji