Add top-level .gitignore file.

Signed-off-by: Eamon Walsh <ewalsh@tycho.nsa.gov>

.gitignore

@@ -0,0 +1,19 @@
+# Note: use "git ls-files -i --exclude-standard" to make sure
+# no tracked files are ignored as a result of any changes.
+
+# Object files
+*.o
+*.lo
+*.so
+*.so.[0-9]
+*.a
+*.s
+*.mo
+
+# Misc
+*.patch
+*.gz
+*~
+
+# Failsafes
+!.gitignore