Use find to find rc files

Using `ls` with a pattern fails if one of the directories is empty.

We don't have to be extremely strict on the filename format, they're
for ordering only, which the sort handles in any case.

zshrc

@@ -2,7 +2,7 @@
 setopt EXTENDED_GLOB
 
 # Source in resources
-ls $HOME/.zsh/zshrc{,_local}.d/([a-zA-Z0-9-]##).zsh | sort -t/ -k6,6 | while read LINE; do
+find "$HOME"/.zsh/zshrc{,_local}.d -type f -name "*.zsh" | sort -t/ -k6,6 | while read LINE; do
 	# If there's a file in zshrc_local.d with the same name as one
 	# in zshrc.d, ignore the file in zshrc.d
 	if [[ "$LINE" =~ "zshrc.d" && -e "$HOME/.zsh/zshrc_local.d/${LINE:t}" ]] ; then