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, 16 insertions, 15 deletions

diff --git a/src/backend/snowball/libstemmer/stem_UTF_8_irish.c b/src/backend/snowball/libstemmer/stem_UTF_8_irish.c
index 9410819dd98..c79b9ee57e6 100644
--- a/src/backend/snowball/libstemmer/stem_UTF_8_irish.c
+++ b/src/backend/snowball/libstemmer/stem_UTF_8_irish.c
@@ -225,24 +225,28 @@ static int r_mark_regions(struct SN_env * z) {
     z->I[1] = z->l;
     z->I[0] = z->l;
     {   int c1 = z->c;
-        {   
+
+        {
             int ret = out_grouping_U(z, g_v, 97, 250, 1);
             if (ret < 0) goto lab0;
             z->c += ret;
         }
         z->I[2] = z->c;
-        {   
+
+        {
             int ret = in_grouping_U(z, g_v, 97, 250, 1);
             if (ret < 0) goto lab0;
             z->c += ret;
         }
         z->I[1] = z->c;
-        {   
+
+        {
             int ret = out_grouping_U(z, g_v, 97, 250, 1);
             if (ret < 0) goto lab0;
             z->c += ret;
         }
-        {   
+
+        {
             int ret = in_grouping_U(z, g_v, 97, 250, 1);
             if (ret < 0) goto lab0;
             z->c += ret;
@@ -258,7 +262,7 @@ static int r_initial_morph(struct SN_env * z) {
     int among_var;
     z->bra = z->c;
     among_var = find_among(z, a_0, 24);
-    if (!(among_var)) return 0;
+    if (!among_var) return 0;
     z->ket = z->c;
     switch (among_var) {
         case 1:
@@ -316,25 +320,22 @@ static int r_initial_morph(struct SN_env * z) {
 }
 
 static int r_RV(struct SN_env * z) {
-    if (!(z->I[2] <= z->c)) return 0;
-    return 1;
+    return z->I[2] <= z->c;
 }
 
 static int r_R1(struct SN_env * z) {
-    if (!(z->I[1] <= z->c)) return 0;
-    return 1;
+    return z->I[1] <= z->c;
 }
 
 static int r_R2(struct SN_env * z) {
-    if (!(z->I[0] <= z->c)) return 0;
-    return 1;
+    return z->I[0] <= z->c;
 }
 
 static int r_noun_sfx(struct SN_env * z) {
     int among_var;
     z->ket = z->c;
     among_var = find_among_b(z, a_1, 16);
-    if (!(among_var)) return 0;
+    if (!among_var) return 0;
     z->bra = z->c;
     switch (among_var) {
         case 1:
@@ -361,7 +362,7 @@ static int r_deriv(struct SN_env * z) {
     int among_var;
     z->ket = z->c;
     among_var = find_among_b(z, a_2, 25);
-    if (!(among_var)) return 0;
+    if (!among_var) return 0;
     z->bra = z->c;
     switch (among_var) {
         case 1:
@@ -406,7 +407,7 @@ static int r_verb_sfx(struct SN_env * z) {
     z->ket = z->c;
     if (z->c - 2 <= z->lb || z->p[z->c - 1] >> 5 != 3 || !((282896 >> (z->p[z->c - 1] & 0x1f)) & 1)) return 0;
     among_var = find_among_b(z, a_3, 12);
-    if (!(among_var)) return 0;
+    if (!among_var) return 0;
     z->bra = z->c;
     switch (among_var) {
         case 1:
@@ -436,7 +437,7 @@ extern int irish_UTF_8_stem(struct SN_env * z) {
         }
         z->c = c1;
     }
-    
+
     {   int ret = r_mark_regions(z);
         if (ret < 0) return ret;
     }