Remove accidentally-committed tilde files

I snuck `src/bindings/*/CMakeLists.txt~` files into one of my
recent commits somehow. This commit removes them, and adds an
explicit `*~` to `.gitignore` to help prevent a repeat occurrence.

Author: ferdnyc

.gitignore

@@ -7,3 +7,4 @@ build/*
 .project
 .cproject
 /.metadata/
+*~