scripts: Add include of std string to gen'ed header

Change-Id: I7a10fa215037d8d30969b8bc071573b489d2412f
diff --git a/layers/generated/vk_enum_string_helper.h b/layers/generated/vk_enum_string_helper.h
index 26180fb..beea896 100644
--- a/layers/generated/vk_enum_string_helper.h
+++ b/layers/generated/vk_enum_string_helper.h
@@ -35,6 +35,7 @@
 #pragma warning( disable : 4065 )
 #endif
 
+#include <string>
 #include <vulkan/vulkan.h>
 
 
diff --git a/scripts/helper_file_generator.py b/scripts/helper_file_generator.py
index 42aeef3..fd76b12 100644
--- a/scripts/helper_file_generator.py
+++ b/scripts/helper_file_generator.py
@@ -427,6 +427,7 @@
             enum_string_helper_header += '#pragma warning( disable : 4065 )\n'
             enum_string_helper_header += '#endif\n'
             enum_string_helper_header += '\n'
+            enum_string_helper_header += '#include <string>\n'
             enum_string_helper_header += '#include <vulkan/vulkan.h>\n'
             enum_string_helper_header += '\n'
             enum_string_helper_header += self.enum_output