Add *~ to .gitignore

One should never add a backup file ending in with ~ to the git repository.

Signed-off-by: Niklaus Giger <niklaus.giger@netstal.com>

.gitignore

@@ -10,6 +10,7 @@
 *.orig
 *.a
 *.o
+*~
 
 #
 # Top-level generic files