otp: Remove warning for not being able to build docs

Since we can automatically download ExDoc, the docs can always be
built, so we remove this warning.

configure.src

@@ -441,22 +441,3 @@ if test "$files" != "$pattern" || test -f erts/CONF_INFO; then
   echo
   echo '*********************************************************************'
 fi
-if test -f "erts/doc/CONF_INFO"; then
-  echo '*********************************************************************'
-  echo '**********************  DOCUMENTATION INFORMATION  ******************'
-  echo '*********************************************************************'
-  echo
-  printf "%-15s: \n" documentation;
-  have_ex_doc="yes"
-  for cmd in `cat erts/doc/CONF_INFO`; do
-	echo "                 $cmd is missing."
-  if test $cmd = "ex_doc"; then
-    have_ex_doc="no"
-  fi
-  done
-  if test $have_ex_doc = "no"; then
-    echo '                 The documentation cannot be built.'
-  fi
-  echo
-  echo '*********************************************************************'
-fi

erts/configure.ac

@@ -462,13 +462,11 @@ fi
 AC_CHECK_PROGS(EX_DOC, ex_doc)
 if test -z "$EX_DOC"; then
   EX_DOC="$ERL_TOP/make/ex_doc_wrapper"
-  echo "ex_doc" >> doc/CONF_INFO
-  AC_MSG_WARN([No 'ex_doc' command found: the documentation cannot be built])
+  AC_MSG_WARN([No 'ex_doc' command found: it will (optionally) be downloaded when building the HTML documentation ])
 fi
 
 AC_CHECK_PROGS(ELIXIR, elixir)
 if test -z "$ELIXIR"; then
-  echo "elixir" >> doc/CONF_INFO
   AC_MSG_WARN([No 'elixir' command found: can't run link checker for the documentation])
 fi