patch 8.2.2550: signal stack size is wrong with latest glibc 2.34

Problem:    Signal stack size is wrong with latest glibc 2.34.
Solution:   Use sysconf(_SC_SIGSTKSZ) if available. (Zdenek Dohnal, closes
            #7895)
diff --git a/src/auto/configure b/src/auto/configure
index 250e5ae..8183499 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -13943,6 +13943,30 @@
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for _SC_SIGSTKSZ via sysconf()" >&5
+$as_echo_n "checking for _SC_SIGSTKSZ via sysconf()... " >&6; }
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <unistd.h>
+int
+main ()
+{
+	(void)sysconf(_SC_SIGSTKSZ);
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }; $as_echo "#define HAVE_SYSCONF_SIGSTKSZ 1" >>confdefs.h
+
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: not usable" >&5
+$as_echo "not usable" >&6; }
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
 # The cast to long int works around a bug in the HP C Compiler
 # version HP92453-01 B.11.11.23709.GP, which incorrectly rejects
 # declarations like `int a3[[(sizeof (unsigned char)) >= 0]];'.