Remove xclip support

Pretty much everyone runs with xsel, so xclip support is becoming more
and more questionable. Just have people use xsel.

clipmenu

@@ -22,9 +22,5 @@ if ! [[ -f "$file" ]]; then
 fi
 
 for selection in clipboard primary; do
-    if type -p xsel >/dev/null 2>&1; then
     xsel --logfile /dev/null -i --"$selection" < "$file"
-    else
-        xclip -sel "$selection" < "$file"
-    fi
 done

clipmenud

@@ -55,13 +55,7 @@ declare -A last_filename
 
 while sleep "${CLIPMENUD_SLEEP:-0.5}"; do
     for selection in clipboard primary; do
-        if type -p xsel >/dev/null 2>&1; then
-            debug 'Using xsel'
         data=$(xsel --logfile /dev/null -o --"$selection"; printf x)
-        else
-            debug 'Using xclip'
-            data=$(xclip -o -sel "$selection"; printf x)
-        fi
 
         debug "Data before stripping: $data"
 
@@ -114,11 +108,7 @@ while sleep "${CLIPMENUD_SLEEP:-0.5}"; do
             # We can't colocate this with the above copying code because
             # https://github.com/cdown/clipmenu/issues/34 requires knowing if
             # we would skip first.
-            if type -p xsel >/dev/null 2>&1; then
             xsel --logfile /dev/null -o --"$selection" | xsel -i --"$selection"
-            else
-                xclip -o -sel "$selection" | xclip -i -sel "$selection"
-            fi
         fi
     done
 done

tests/test-perf

@@ -35,7 +35,6 @@ shopt -s expand_aliases
 
 alias dmenu=:
 alias xsel=:
-alias xclip=:
 
 EOF