Add support for blackfin arch.

Fixes compilation error:
../../../../CPP/myWindows/mySplitCommandLine.cpp:99:8: error: #error ENDIANNESS

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
(Patch sent upstream: https://sourceforge.net/p/p7zip/patches/33/

diff -uNr p7zip_15.14.1.org/C/CpuArch.h p7zip_15.14.1/C/CpuArch.h
--- p7zip_15.14.1.org/C/CpuArch.h	2016-02-17 07:27:16.000000000 +0100
+++ p7zip_15.14.1/C/CpuArch.h	2016-06-08 19:47:49.000000000 +0200
@@ -66,6 +66,7 @@
     || defined(__MIPSEL__) \
     || defined(__MIPSEL) \
     || defined(_MIPSEL) \
+    || defined(__BFIN__) \
     || (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__))
   #define MY_CPU_LE
 #endif