In the previous implementation, std::find() returned fns.end() several times,
which caused an "Address boundary error" in std::sort if the preferred
font-index was set to m_fonts.size() + 1.
This commit reimplements the font prioritization with a simple swap.
Reproduction steps:
- Start polybar with the following config:
[bar/top]
font-0 = NotoSans-Regular:size=8;0
font-1 = MaterialIcons:size=10;0
modules-left = date
[module/date]
type = internal/date
date = %Y-%m-%d
label-font = 3 ; invalid index
701102d44b