Crash on system without fonts

[maleadt]

Cairo.jl currently fails PkgEval because Pango doesn't like a system without fonts (such as the bare rootfs used by PkgEval):

Test Summary:     |Time
IOBuffer Rooting  | None  0.5s
Test Summary:   | Pass  Total  Time
Image Surface   |    7      7  0.5s
Test Summary:   | Pass  Total  Time
Conversions     |    7      7  1.7s
Test Summary:   | Pass  Total  Time
TexLexer        |    1      1  0.3s

(process:17): Pango-CRITICAL **: 07:02:45.820: pango_font_get_hb_font: assertion 'PANGO_IS_FONT (font)' failed

[17] signal (11.1): Segmentation fault
in expression starting at /home/pkgeval/.julia/packages/Cairo/smWIA/samples/sample_pango_text.jl:20
hb_ot_metrics_get_position at /home/pkgeval/.julia/artifacts/ee20a84d0166c074dfa736b642902dd87b4da48d/lib/libharfbuzz.so (unknown line)
collect_font_scale at /workspace/srcdir/pango-1.50.9/build/../pango/itemize.c:1080 [inlined]
apply_font_scale at /workspace/srcdir/pango-1.50.9/build/../pango/itemize.c:1200
post_process_items at /workspace/srcdir/pango-1.50.9/build/../pango/itemize.c:1529 [inlined]
pango_itemize_post_process_items at /workspace/srcdir/pango-1.50.9/build/../pango/itemize.c:1580
pango_layout_check_lines at /workspace/srcdir/pango-1.50.9/build/../pango/pango-layout.c:4914
pango_layout_get_extents_internal at /workspace/srcdir/pango-1.50.9/build/../pango/pango-layout.c:2925
pango_layout_get_pixel_size at /workspace/srcdir/pango-1.50.9/build/../pango/pango-layout.c:3194
get_layout_size at /home/pkgeval/.julia/packages/Cairo/smWIA/src/Cairo.jl:1184 [inlined]

This isn't really a Cairo.jl issue, but it does prevent the package (and downstream packages like Gadfly.jl) to get monitored by PkgEval, which is bad. For now, I've implemented a workaround in PkgEval.jl, JuliaCI/PkgEval.jl#154, providing a simple font in the rootfs we use. However, it would be better to fix this without a workaround. Note that I'm not asking for a hack in the Cairo.jl test suite (ENV["PkgEval"] && download(...)), but rather a fix to Cairo.jl (or the underlying libraries) so that this doesn't segfault, even on a badly-configured system.

I also came across https://gitlab.alpinelinux.org/alpine/aports/-/issues/13686 which noted that this is a Pango bug fixed in Pango 1.50.7, but the JLL is already using a newer version (and GNOME's gitlab seems down so I can't inspect the actual fix)...