Only ignore config.h in the root directory.

Add missing Xcode config.h.

.gitignore

@@ -1,7 +1,7 @@
 *.o
 Makefile
 autom4te.cache
-config.h
+/config.h
 config.log
 config.status
 doc/mxml.d

xcode/config.h

@@ -0,0 +1,74 @@
+/*
+ * Configuration file for Mini-XML, a small XML file parsing library.
+ *
+ * https://www.msweet.org/mxml
+ *
+ * Copyright © 2003-2019 by Michael R Sweet.
+ *
+ * Licensed under Apache License v2.0.  See the file "LICENSE" for more
+ * information.
+ */
+
+/*
+ * Include necessary headers...
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <ctype.h>
+
+
+/*
+ * Version number...
+ */
+
+#define MXML_VERSION "Mini-XML v3.0"
+
+
+/*
+ * Inline function support...
+ */
+
+#define inline
+
+
+/*
+ * Long long support...
+ */
+
+#define HAVE_LONG_LONG 1
+
+
+/*
+ * Do we have the *printf() functions?
+ */
+
+#define HAVE_SNPRINTF 1
+#define HAVE_VASPRINTF 1
+#define HAVE_VSNPRINTF 1
+
+
+/*
+ * Do we have the strXXX() functions?
+ */
+
+#define HAVE_STRDUP 1
+#define HAVE_STRLCAT 1
+#define HAVE_STRLCPY 1
+
+
+/*
+ * Do we have threading support?
+ */
+
+#define HAVE_PTHREAD_H 1
+
+
+/*
+ * Define prototypes for string functions as needed...
+ */
+
+extern char	*_mxml_strdupf(const char *, ...);
+extern char	*_mxml_vstrdupf(const char *, va_list);