Merge commit '7d7ea52' into bfgminer-3.5.x

Conflicts:
	configure.ac

configure.ac

@@ -77,8 +77,6 @@ AC_CHECK_HEADERS([sys/prctl.h])
 AC_CHECK_HEADERS([sys/file.h])
 AC_CHECK_HEADERS([linux/spi/spidev.h])
 
-AC_CHECK_HEADERS([sys/file.h])
-
 AC_CHECK_MEMBER([struct i2c_msg.buf],[
 	true
 ],[