Bug 781431 - A few minor build system improvements. r=ted

1. mozconfig2client-mk still refers to $HOME/.mozconfig, even though we
removed it a while ago. Thanks to Neil for pointing it out.
2. MOZCONFIG_FIND and MOZCONFIG_MODULES are no longer used by client.mk.
3. Make CONFIG_GUESS a script that runs just once per client.mk invocation.

--HG--
extra : rebase_source : ec75ebcc5cea004f64abafb8a219e828234237de

build/autoconf/mozconfig2client-mk

@@ -10,11 +10,10 @@
 # See mozconfig2configure for more details
 
 print_header() {
-  _mozconfig=${MOZCONFIG:-$HOME/.mozconfig}
   cat <<EOF
 # gmake
 # This file is automatically generated for client.mk.
-# Do not edit. Edit $_mozconfig instead.
+# Do not edit. Edit $FOUND_MOZCONFIG instead.
 
 EOF
 }
@@ -53,8 +52,6 @@ scriptdir=`dirname $0`
 topsrcdir=$1
 opts=""
 
-print_header
-
 # If the path changes, configure should be rerun
 echo "# PATH=$PATH"
 
@@ -72,6 +69,7 @@ fi
 if [ -n $isfoundset ]; then
   if [ "$FOUND_MOZCONFIG" ]
   then
+    print_header
     . "$FOUND_MOZCONFIG"
   fi
   echo "export FOUND_MOZCONFIG := $FOUND_MOZCONFIG"

client.mk

@@ -70,7 +70,7 @@ PYTHON ?= python
 
 CONFIG_GUESS_SCRIPT := $(wildcard $(TOPSRCDIR)/build/autoconf/config.guess)
 ifdef CONFIG_GUESS_SCRIPT
-  CONFIG_GUESS = $(shell $(CONFIG_GUESS_SCRIPT))
+  CONFIG_GUESS := $(shell $(CONFIG_GUESS_SCRIPT))
 endif
 
 
@@ -92,8 +92,6 @@ endif
 # See build pages, http://www.mozilla.org/build/ for how to set up mozconfig.
 
 MOZCONFIG_LOADER := build/autoconf/mozconfig2client-mk
-MOZCONFIG_FINDER := build/autoconf/mozconfig-find 
-MOZCONFIG_MODULES := build/unix/uniq.pl
 
 define CR