[Bash-autocompletion] Invoke clang where user called

[yamaguchi]

Summary

When user build clang and used completion Eg. build/bin/clang -fno[tab] , we want to invoke build/bin/clang --autocomplete=-fno , rather than clang --autocomplete=-fno .

[v.g.vassilev]

LGTM.

[ruiu]

LGTM

clang/utils/bash-autocomplete.sh

_clang()
   elif [[ "$w1" == -* ]]; then
     # -foo <tab> or -foo bar<tab>
     arg="$w1,$cur"
   elif [[ "$w2" == -* && "$w1" == '=' ]]; then
     # -foo=bar<tab>
     arg="$w2=,$cur"
   fi
 
-  flags=$( clang --autocomplete="$arg" 2>/dev/null )
+  flags=$( "${COMP_WORDS[0]}" --autocomplete="$arg" 2>/dev/null )
   # If clang is old that it does not support --autocomplete,
   # fall back to the filename completion.
   if [[ "$?" != 0 ]]; then
     _filedir
     return
   fi
 
   if [[ "$cur" == '=' ]]; then