build: fix dependencies on AIX

Addon tests were still starting to run before the node exp file
creation was complete.

- remove process_outputs_as_sources as it did not fix the
  problem
- update create_expfile.sh so that exp file is created in a
  temporary file and then renamed to final name so that
  file is only visible once it is complete
- update target used in building Addons so that for
  AIX it depends on the exp file being available

PR-URL: https://github.com/nodejs/node/pull/8285
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Myles Borins <myles.borins@gmail.com>

tools/create_expfile.sh

@@ -36,7 +36,7 @@
 echo "Searching $1 to write out expfile to $2"
 
 # this special sequence must be at the start of the exp file
-echo "#!." > $2
+echo "#!." > $2.tmp
 
 # pull the symbols from the .a files
 find $1 -name "*.a" | grep -v gtest \
@@ -45,4 +45,6 @@ find $1 -name "*.a" | grep -v gtest \
       if ((($2 == "T") || ($2 == "D") || ($2 == "B")) &&
           (substr($3,1,1) != ".")) { print $3 }
     }' \
-  | sort -u >> $2
+  | sort -u >> $2.tmp
+
+mv -f $2.tmp $2