Merge branch 'js/ci-gcc-12-fixes' into maint

Fixes real problems noticed by gcc 12 and works around false
positives.
source: <pull.1238.git.1653351786.gitgitgadget@gmail.com>

* js/ci-gcc-12-fixes:
  dir.c: avoid "exceeds maximum object size" error with GCC v12.x
  nedmalloc: avoid new compile error
  compat/win32/syslog: fix use-after-realloc

compat/nedmalloc/nedmalloc.c

@@ -323,7 +323,6 @@ static NOINLINE void RemoveCacheEntries(nedpool *p, threadcache *tc, unsigned in
 }
 static void DestroyCaches(nedpool *p) THROWSPEC
 {
-	if(p->caches)
 	{
 		threadcache *tc;
 		int n;

compat/win32/syslog.c

@@ -43,6 +43,7 @@ void syslog(int priority, const char *fmt, ...)
 	va_end(ap);
 
 	while ((pos = strstr(str, "%1")) != NULL) {
+		size_t offset = pos - str;
 		char *oldstr = str;
 		str = realloc(str, st_add(++str_len, 1));
 		if (!str) {
@@ -50,6 +51,7 @@ void syslog(int priority, const char *fmt, ...)
 			warning_errno("realloc failed");
 			return;
 		}
+		pos = str + offset;
 		memmove(pos + 2, pos + 1, strlen(pos));
 		pos[1] = ' ';
 	}

dir.c

@@ -3081,6 +3081,15 @@ char *git_url_basename(const char *repo, int is_bundle, int is_bare)
 			end--;
 	}
 
+	/*
+	 * It should not be possible to overflow `ptrdiff_t` by passing in an
+	 * insanely long URL, but GCC does not know that and will complain
+	 * without this check.
+	 */
+	if (end - start < 0)
+		die(_("No directory name could be guessed.\n"
+		      "Please specify a directory on the command line"));
+
 	/*
 	 * Strip trailing port number if we've got only a
 	 * hostname (that is, there is no dir separator but a