Updating new Xcode project

This provides additional improvements and updates for building
Audacity using Xcode 5.1 or above.

The whole configure/makefile system is no longer used during
normal builds.  During library additions/updates it used to
regenerated the headers in mac/config.

mac/config/i386/lib-src/libsoxr/soxr-config.h

@@ -0,0 +1,52 @@
+/* SoX Resampler Library      Copyright (c) 2007-13 robs@users.sourceforge.net
+ * Licence for this file: LGPL v2.1                  See LICENCE for details. */
+
+#if !defined soxr_config_included
+#define soxr_config_included
+
+#define HAVE_SINGLE_PRECISION 1
+#define HAVE_DOUBLE_PRECISION 1
+#define HAVE_AVFFT            0
+#define HAVE_SIMD             1
+#define HAVE_FENV_H           1
+#define HAVE_LRINT            1
+#define WORDS_BIGENDIAN       0
+
+#include <limits.h>
+
+#undef bool
+#undef false
+#undef true
+#define bool int
+#define false 0
+#define true 1
+
+#undef int16_t
+#undef int32_t
+#undef int64_t
+#undef uint32_t
+#undef uint64_t
+#define int16_t short
+#if LONG_MAX > 2147483647L
+  #define int32_t int
+  #define int64_t long
+#elif LONG_MAX < 2147483647L
+#error this library requires that 'long int' has at least 32-bits
+#else
+  #define int32_t long
+  #if defined _MSC_VER
+    #define int64_t __int64
+  #else
+    #define int64_t long long
+  #endif
+#endif
+#define uint32_t unsigned int32_t
+#define uint64_t unsigned int64_t
+
+#endif
+#if defined(__BIG_ENDIAN__)
+#undef WORDS_BIGENDIAN
+#define WORDS_BIGENDIAN 1
+#endif
+#undef HAVE_SIMD
+#define HAVE_SIMD 0