[build] Disable clang-format on generated code

Nice to have, but would make maintain the templates a lot harder.

src/mbgl/style/layers/layer.cpp.ejs

@@ -3,6 +3,8 @@
   const layoutProperties = locals.layoutProperties;
   const paintProperties = locals.paintProperties;
 -%>
+// clang-format off
+
 // This file is generated. Edit scripts/generate-style-code.js, then run `make style-code`.
 
 #include <mbgl/style/layers/<%- type.replace('-', '_') %>_layer.hpp>
@@ -317,3 +319,5 @@ Mutable<Layer::Impl> <%- camelize(type) %>Layer::mutableBaseImpl() const {
 
 } // namespace style
 } // namespace mbgl
+
+// clang-format on