coredump: fail on unsupported architectures early

Currently coredump only works on x86_64. Fail early on any other
architecture.

Signed-off-by: Adrian Reber <areber@redhat.com>

coredump/coredump

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+import platform
 import argparse
 import os
 import sys
@@ -36,6 +37,10 @@ def main():
 
     opts = vars(parser.parse_args())
 
+    if platform.machine() != 'x86_64':
+        print('ERROR: %s only supported on x86_64' % sys.argv[0])
+        sys.exit(1)
+
     try:
         coredump(opts)
     except SystemExit as error: