meson: unify exported symbol versions with autotools

libnice.so created by autotools has its symbols bound to the default
'Base' version node, whereas Meson build arbitrarily introduced a
version node named 'libnice'. This breaks tools like dpkg-gensymbols
that track changes in exported symbols through several releases of the
library.

Remove 'libnice' version and revert back to using unspecified version.
7 jobs for symver in 12 minutes and 49 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #80672
build autotools

00:01:21

passed #80673
build meson

00:02:00

 
  Test
passed #80683
distcheck autotools

00:02:02

passed #80677
doc-and-install meson

00:07:23

passed #80674
test autotools

00:01:35

failed #80676
allowed to fail
test meson

00:02:15

canceled #80675
distcheck autotools

00:16:33

 
Name Stage Failure
failed
test meson Test
--- command ---
BUILT_WITH_MESON='1' /builds/xhaakon/libnice/build/tests/nice-test-new-dribble
-------

Full log written to /builds/xhaakon/libnice/build/meson-logs/testlog.txt
Uploading artifacts...
build/meson-logs/: found 4 matching files
Uploading artifacts to coordinator... ok
id=80676 responseStatus=201 Created token=FqfwsiTG
ERROR: Job failed: exit code 1