popuplayout had two refit stages for a work area shorter than one
padded row — 40 pixels — and popupdraw re-checked the layout it had
just been handed, against an Imgh that bounded no buffer any more.
Pango and Cairo abort rather than return nil, so textinit is void and
the layout is never nil; the stride Cairo computes for RGB24 is w*4 by
definition; and textdraw set the layout's width and ellipsis twice.
font.c exported three wrappers for one function, and the fit == -1 mode
existed only for the tests; textdraw() takes fit and colour. win.c
tested the empty picture in the thread and again in winshow, interned
two atoms by hand next to getatom(), kept a consumer-side drain that the
producer's already guarantees never finds anything, zeroed ten globals
before returning from the only thread that read them, and re-checked
sizes that resizebacking had just established. The page marker is laid
out once and drawn from the layout instead of being recomputed.
