oe-setup-builddir: fix TEMPLATECONF error message

This directory shouldn't contain local.conf and bblayers.conf - just
templates for them; except it doesn't have to contain those, it just has
to exist to pass this test. Change the error message accordingly, and
mention TEMPLATECONF so that the user has at least some context.

(From OE-Core rev: 61adaaa4348c670769f8750223977dbefe369ffb)

(From OE-Core rev: 3136666fee621d94ec4c48e706f0dad3b6b6f08c)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/oe-setup-builddir

@@ -61,7 +61,7 @@ if [ -n "$TEMPLATECONF" ]; then
             TEMPLATECONF="$OEROOT/$TEMPLATECONF"
         fi
         if [ ! -d "$TEMPLATECONF" ]; then
-            echo >&2 "Error: '$TEMPLATECONF' must be a directory containing local.conf & bblayers.conf"
+            echo >&2 "Error: TEMPLATECONF value points to nonexistent directory '$TEMPLATECONF'"
             exit 1
         fi
     fi