Update .gitignore files

Add kmod-* prefixed tool names, add 'tags' in root directory (for ctags,
matches cscope.out ignore already in there), and prefix tools/ entries
with '/' so they are absolute ignores and don't apply to subdirectories.
diff --git a/.gitignore b/.gitignore
index 79b5f65..8d7c74a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,3 +20,4 @@
 *~
 .*.swp
 cscope.out
+tags