Delete bundled copy of NSS and replace with README.

nss/lib/freebl/nss_build_config_mac.h

Index: nss/lib/freebl/nss_build_config_mac.h
diff --git a/nss/lib/freebl/nss_build_config_mac.h b/nss/lib/freebl/nss_build_config_mac.h
deleted file mode 100644
index de95cf96b6fedf075862ecfddbbfbbde7dfb7b00..0000000000000000000000000000000000000000
--- a/nss/lib/freebl/nss_build_config_mac.h
+++ /dev/null
@@ -1,40 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-/*
- * This header defines the configuration macros used by lib/freebl files
- * for iOS and Mac OS X. It is included with the -include compiler flag.
- */
-#if !defined(__APPLE__)
-#error This file is intended for iOS and Mac OS X only
-#endif
-
-#if defined(__i386__)
-
-#define NSS_X86_OR_X64 1
-#define NSS_X86 1
-#define i386 1
-
-#elif defined(__x86_64__)
-
-#define NSS_USE_64 1
-#define NSS_X86_OR_X64 1
-#define NSS_X64 1
-
-#elif defined(__arm__)
-
-#define MP_ASSEMBLY_MULTIPLY 1
-#define MP_ASSEMBLY_SQUARE 1
-#define MP_USE_UINT_DIGIT 1
-#define SHA_NO_LONG_LONG 1
-
-#elif defined(__aarch64__)
-
-#define NSS_USE_64 1
-
-#else
-
-#error unknown processor architecture
-
-#endif