Issue 9309 - Regression (2.061): -O -release generates wrong code

http://d.puremagic.com/issues/show_bug.cgi?id=9309

By merging pull #1110, escapeShellArgument!allocator is marked as PUREstrong.
But it is a nested function, and its call may have a side effect through
its hidden context pointer. So glue layer cannot remove its call.