target: write gmon.out according to target endianness

After profiling gmon.out was being written in little endian format only
which would cause gprof to issue and error and exit on big endian targets.

Change-Id: I526a40adae0f9a439fc5b77cef30fda228198b48
Signed-off-by: Jose de Sousa <jose.t.de.sousa@gmail.com>
Reviewed-on: http://openocd.zylin.com/2168


Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>