https://github.com/nzbgetcom/nzbget/commit/412d9e5b732c1cf39aac266dcf97bf097f85bc58

From 412d9e5b732c1cf39aac266dcf97bf097f85bc58 Mon Sep 17 00:00:00 2001
From: Louis Sautier <sautier.louis@gmail.com>
Date: Tue, 16 Jul 2024 05:41:47 +0200
Subject: [PATCH] Fix: add missing HAVE_ALLOCA_H definition for regex (#308)
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Without this, the build fails with:
```
/var/tmp/portage/net-nntp/nzbget-24.1/work/nzbget-24.1/lib/regex/regex.c: In function ‘set_regs’:
/var/tmp/portage/net-nntp/nzbget-24.1/work/nzbget-24.1/lib/regex/regex.c:7701:39: error: implicit declaration of function ‘alloca’; did you mean ‘calloc’? [-Wimplicit-function-declaration]                        7701 |         prev_idx_match = (regmatch_t*)alloca(nmatch * sizeof(regmatch_t));
      |                                       ^~~~~~
      |                                       calloc
```
--- a/cmake/config.h.in
+++ b/cmake/config.h.in
@@ -134,6 +134,9 @@
 /* Define to 1 if you have the <unistd.h> header file. */
 #cmakedefine HAVE_UNISTD_H @HAVE_UNISTD_H@
 
+/* Define to 1 if you have the <alloca.h> header file. */
+#cmakedefine HAVE_ALLOCA_H @HAVE_ALLOCA_H@
+
 /* Define to 1 if variadic macros are supported */
 #cmakedefine HAVE_VARIADIC_MACROS @HAVE_VARIADIC_MACROS@
 
--- a/cmake/posix.cmake
+++ b/cmake/posix.cmake
@@ -120,6 +120,7 @@ check_include_file(strings.h HAVE_STRINGS_H)
 check_include_file(string.h HAVE_STRING_H)
 check_include_file(sys/stat.h HAVE_SYS_STAT_H)
 check_include_file(unistd.h HAVE_UNISTD_H)
+check_include_file(alloca.h HAVE_ALLOCA_H)
 
 check_library_exists(pthread pthread_create "" HAVE_PTHREAD_CREATE) 
 check_library_exists(socket socket "" HAVE_SOCKET)