CROSS_PREFIX fixes:
-Enable override of epiphany cross prefix
-Use -m in uname (-p reports "unknown" in some distros)
Is this logic really needed?
Remove default CROSS_COMPILE prefix
Merge pull request #23 from sctincman/prefix-fixes

Cross-compiler prefix fixes
Fixed a segfault due to fprintf being called with an uninitialized file pointer.
        Renamed global diagnostics file pointer from fd to diag_fd.
        Changed explicit fprintf calls to warnx calls.
Merge pull request #24 from adapteva/bcxcube-diag-crash

Fixed a segfault due to fprintf being called with an uninitialized file ...