AI 145720: Fixed tracedmdump() by correcting the KERNEL path.

Merged 145709 from donut.
  BUG=1630077

Automated import of CL 145720

envsetup.sh

@@ -817,7 +817,7 @@ function tracedmdump()
         return
     fi
     local prebuiltdir=$(getprebuilt)
-    local KERNEL=$T/prebuilt/android-arm/vmlinux-qemu
+    local KERNEL=$T/prebuilt/android-arm/kernel/vmlinux-qemu
 
     local TRACE=$1
     if [ ! "$TRACE" ] ; then
@@ -825,6 +825,11 @@ function tracedmdump()
         return
     fi
 
+    if [ ! -r "$KERNEL" ] ; then
+        echo "Error: cannot find kernel: '$KERNEL'"
+        return
+    fi
+
     local BASETRACE=$(basename $TRACE)
     if [ "$BASETRACE" = "$TRACE" ] ; then
         TRACE=$ANDROID_PRODUCT_OUT/traces/$TRACE