layers: Add new source file to stats script

Missed this one.
diff --git a/layers/vk_validation_stats.py b/layers/vk_validation_stats.py
index 092438b..6d563c4 100755
--- a/layers/vk_validation_stats.py
+++ b/layers/vk_validation_stats.py
@@ -49,6 +49,7 @@
 'descriptor_sets.cpp',
 'parameter_validation.cpp',
 'object_tracker.cpp',
+'shader_validation.cpp',
 'buffer_validation.cpp',
 'swapchain.cpp'
 ]