configure : Incorrect syntax in configure

Check to see if postproc was enabled when enabling the
postproc visualizer was wrong.

Fix for bug introduced in Change Ia74f357d

Change-Id: I4bee9ad2caee3cfe3bac6972047f6af7c54cad4e

configure

@@ -538,8 +538,9 @@ process_toolchain() {
     # Other toolchain specific defaults
     case $toolchain in x86*|ppc*|universal*) soft_enable postproc;; esac
 
-    enabled postproc_visualizer && {enabled postproc \
-        || die "postproc_visualizer requires postproc to be enabled"}
+    if enabled postproc_visualizer; then
+        enabled postproc || die "postproc_visualizer requires postproc to be enabled"
+    fi
 }