Return non-zero if can't locate top of the tree in m/mm/mmm.

Bug: 20017058
Change-Id: I85fac71061673d00a1b583ad13afc8567d794cd6
diff --git a/envsetup.sh b/envsetup.sh
index f93c07d..bd77895 100644
--- a/envsetup.sh
+++ b/envsetup.sh
@@ -672,6 +672,7 @@
         $DRV make -C $T -f build/core/main.mk $@
     else
         echo "Couldn't locate the top of the tree.  Try setting TOP."
+        return 1
     fi
 }
 
@@ -710,8 +711,10 @@
         local M=`echo $M|sed 's:'$T'/::'`
         if [ ! "$T" ]; then
             echo "Couldn't locate the top of the tree.  Try setting TOP."
+            return 1
         elif [ ! "$M" ]; then
             echo "Couldn't locate a makefile from the current directory."
+            return 1
         else
             for ARG in $@; do
                 case $ARG in
@@ -774,6 +777,7 @@
         ONE_SHOT_MAKEFILE="$MAKEFILE" $DRV make -C $T -f build/core/main.mk $DASH_ARGS $MODULES $ARGS
     else
         echo "Couldn't locate the top of the tree.  Try setting TOP."
+        return 1
     fi
 }
 
@@ -786,6 +790,7 @@
   else
     if [ ! "$T" ]; then
       echo "Couldn't locate the top of the tree.  Try setting TOP."
+      return 1
     fi
     local MY_PWD=`PWD= /bin/pwd|sed 's:'$T'/::'`
     $DRV make -C $T -f build/core/main.mk $@ all_modules BUILD_MODULES_IN_PATHS="$MY_PWD"
@@ -825,6 +830,7 @@
     $DRV make -C $T -f build/core/main.mk $DASH_ARGS $ARGS all_modules BUILD_MODULES_IN_PATHS="$MODULE_PATHS"
   else
     echo "Couldn't locate the top of the tree.  Try setting TOP."
+    return 1
   fi
 }