Change the soname of libpurple to libpurple3
Review Request #2182 — Created Jan. 8, 2023 and submitted
I ran into an issue compiling a purple2 plugin on my Debian unstable machine. I tracked it down to /usr/local/lib/x86_64-linux-gnu being before /usr/local/lib in my ld.so.conf. This meant that the linker found /usr/local/lib/x86_64-linux-gnu/libpurple.so.20.0.0 which is purple3, before it found /usr/local/lib/libpurple.so.14.0.0 which is purple2. This obviously caused the plugin to be unloadable in purple2/pidgin2. So to avoid this issue for others, changing the soname just makes sense and is what other libraries like GTK already do to support running both side by side.
Wiped by build directory then ran the unit tests and pidgin3 and verified everything looked alright.