temp/gnome-shell-mobile: don't build against libsoup2
Fixes #1735 (closed). I managed to track down the exact issue: there was a mismatch between the libsoup versions loaded in the GNOME shell:
(gnome-shell:2633): libsoup-ERROR **: 03:37:53.700: libsoup2 symbols detected. Using libsoup2 and libsoup3 in the same process is not supported.
== Stack trace for context 0xffff800e7630 ==
#0 ffff7f61bf98 i resource:///org/gnome/shell/ui/dateMenu.js:377 (34ab42644290 @ 73)
#1 ffff7f61bec8 i resource:///org/gnome/shell/ui/dateMenu.js:352 (34ab426441a0 @ 486)
#2 ffff7f61be28 i resource:///org/gnome/shell/ui/dateMenu.js:316 (34ab426444c0 @ 27)
#3 ffff7f61bd38 i resource:///org/gnome/shell/ui/dateMenu.js:926 (34ab42644ec0 @ 1109)
#4 ffff7f61bc98 i resource:///org/gnome/shell/ui/panelMenu.js:11 (297df944aba0 @ 27)
#5 ffff7f61bbf8 i resource:///org/gnome/shell/ui/panelMenu.js:97 (297df944ae70 @ 27)
#6 ffff7f61bb58 i resource:///org/gnome/shell/ui/dateMenu.js:835 (34ab42645150 @ 27)
#7 ffff7f61baa8 i resource:///org/gnome/shell/ui/panel.js:751 (34ab426356f0 @ 159)
#8 ffff7f61b9e0 i resource:///org/gnome/shell/ui/panel.js:762 (34ab42635740 @ 109)
#9 ffff7f61b940 i resource:///org/gnome/shell/ui/panel.js:709 (34ab42635650 @ 109)
#10 ffff7f61b898 i resource:///org/gnome/shell/ui/panel.js:482 (34ab4262fec0 @ 998)
#11 ffff7f61b7f8 i resource:///org/gnome/shell/ui/panel.js:432 (34ab426359c0 @ 27)
#12 ffff7f61b748 i resource:///org/gnome/shell/ui/main.js:248 (2d2df2bc2060 @ 670)
#13 ffff7f61b6a0 i resource:///org/gnome/shell/ui/main.js:186 (2d2df2bb4ec0 @ 339)
#14 ffff7f61b618 i resource:///org/gnome/shell/ui/init.js:6 (2d2df2b8c560 @ 63)
#15 ffffd537d010 b self-hosted:2325 (2d2df2b739c0 @ 674)
#16 ffff7f61b548 i self-hosted:2286 (2d2df2b73970 @ 328)
gnome-session-binary[2502]: WARNING: Application 'org.gnome.Shell.desktop' killed by signal 5
Disabling the soup2
option fixed the issue, and gnome-mobile-shell boots again \o/