pythongh-109631: Allow interruption of short repeated regex matches

Counting for signal checking now continues in new match from the point where
it ended in the previous match instead of starting from 0.

Misc/NEWS.d/next/Library/2023-09-25-23-00-37.gh-issue-109631.eWSqpO.rst

@@ -0,0 +1,3 @@
+:mod:`re` functions such as :func:`re.findall`, :func:`re.split`,
+:func:`re.search` and :func:`re.sub` which perform short repeated matches
+can now be interrupted by user.

Modules/_sre/sre.h

@@ -95,6 +95,7 @@ typedef struct {
     size_t data_stack_base;
     /* current repeat context */
     SRE_REPEAT *repeat;
+    unsigned int sigcount;
 } SRE_STATE;
 
 typedef struct {

Modules/_sre/sre_lib.h

@@ -564,7 +564,7 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
     Py_ssize_t alloc_pos, ctx_pos = -1;
     Py_ssize_t ret = 0;
     int jump;
-    unsigned int sigcount=0;
+    unsigned int sigcount = state->sigcount;
 
     SRE(match_context)* ctx;
     SRE(match_context)* nextctx;
@@ -1567,8 +1567,10 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
     ctx_pos = ctx->last_ctx_pos;
     jump = ctx->jump;
     DATA_POP_DISCARD(ctx);
-    if (ctx_pos == -1)
+    if (ctx_pos == -1) {
+        state->sigcount = sigcount;
         return ret;
+    }
     DATA_LOOKUP_AT(SRE(match_context), ctx, ctx_pos);
 
     switch (jump) {