Fix word-wrapped tooltip text not showing by aligning to pixel grid.

With rBae43872ad572eb3e6ad1ebfd02921fc2403059bc blf_font_height_max_ft_pix gives subpixel result while blf_font_height_max gives a pixel-aligned integer value.

When tooptips are calculating the size of their area, they assume a line height from blf_font_height_max. However, when processing multiline content in blf_font_wrap_apply that function uses a line height of blf_font_height_max_ft_pix. Therefore the height of lines will be slightly taller than the room made for them - and they therefore get clipped out.

This patch just forces the line height in blf_font_wrap_apply to be pixel truncated. Ultimately Campbell might want to address this a little differently, but this at least fixes the issue.