Update to latest Snowball sources.

It's been some time since we did this, partly because the upstream
snowball project hasn't formally tagged a new release since 2021.
The main motivation for doing it now is to absorb a bug fix
(their commit e322673a841d9abd69994ae8cd20e191090b6ef4), which
prevents a null pointer dereference crash if SN_create_env() gets
a malloc failure at just the wrong point.  We'll patch the back
branches with only that change, but we might as well do the full
sync dance on HEAD.

Aside from a bunch of mostly-minor tweaks to existing stemmers, this
update adds a new stemmer for Estonian.  It also removes the existing
stemmer for Romanian using ISO-8859-2 encoding.  Upstream apparently
concluded that ISO-8859-2 doesn't provide an adequate representation
of some Romanian characters, and the UTF-8 implementation should be
used instead.

While at it, update the README's instructions for doing a sync,
which have not been adjusted during the addition of meson tooling.

Thanks to Maksim Korotkov for discovering the null-pointer
bug and submitting the fix to upstream snowball.

Reported-by: Maksim Korotkov <m.korotkov@postgrespro.ru>
Discussion: https://postgr.es/m/1d1a46-67ab1000-21-80c451@83151435

1 files changed, 1 insertions, 1 deletions

diff --git a/src/backend/snowball/libstemmer/api.c b/src/backend/snowball/libstemmer/api.c
index 375938e6d13..358f5633b28 100644
--- a/src/backend/snowball/libstemmer/api.c
+++ b/src/backend/snowball/libstemmer/api.c
@@ -34,7 +34,7 @@ error:
 extern void SN_close_env(struct SN_env * z, int S_size)
 {
     if (z == NULL) return;
-    if (S_size)
+    if (z->S)
     {
         int i;
         for (i = 0; i < S_size; i++)