gitignore: ignore patches in root directory

This will have GIT ignore patches in root directory, as created
when using "git format-patch".

.gitignore

@@ -1,28 +1,30 @@
-*.o
-.DS_Store
-.*.swp
-/env
-/dl
-/.config
-/.config.old
-/bin
-/build_dir
-/staging_dir
-/tmp
-/logs
-/feeds
-/feeds.conf
-/files
-/overlay
-/package/feeds
-/package/openwrt-packages
-key-build*
-*.orig
-*.rej
-*~
-.#*
-*#
-.emacs.desktop*
-TAGS*~
-git-src
-.git-credentials
+*.o
+.DS_Store
+.*.swp
+/env
+/dl
+/.config
+/.config.old
+/bin
+/build_dir
+/staging_dir
+/tmp
+/logs
+/feeds
+/feeds.conf
+/files
+/overlay
+/package/feeds
+/package/openwrt-packages
+/*.patch
+key-build*
+*.orig
+*.rej
+*~
+.#*
+*#
+.emacs.desktop*
+TAGS*~
+git-src
+.project
+.cproject