Get terminal capabilities using a zsh builtin for portability

powerlevel9k.zsh-theme

@@ -947,7 +947,7 @@ function zle-keymap-select {
 powerlevel9k_init() {
   # Display a warning if the terminal does not support 256 colors
   local term_colors
-  term_colors=$(tput colors)
+  term_colors=$(echotc Co)
   if (( term_colors < 256 )); then
     print -P "%F{red}WARNING!%f Your terminal supports less than 256 colors!"
     print -P "You should put: %F{blue}export TERM=\"xterm-256color\"%f in your \~\/.zshrc"