Add gitignore files

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@7385 3c298f89-4303-0410-b956-a3cf2f4a3e73

.gitignore

+.config*
+bin
+build_*
+toolchain_build_*
+staging_dir_*
+tmp
+dl
+tool_build

scripts/config/.gitignore

+*.o
+lxdialog
+conf
+mconf
+*.*.c