bash: install cargo and use that for exa etc.

bashrc

@@ -147,6 +147,11 @@ fi
 
 [ -f ~/.fzf.bash ] && source ~/.fzf.bash
 
+# Not version controlled, it's system specific.
+if [ -r $HOME/.cargo/env ] ; then
+  source $HOME/.cargo/env
+fi
+
 # Load any supplementary scripts
 if [ -d "$HOME"/.bashrc.d ] ; then
     for config in "$HOME"/.bashrc.d/*.bash ; do