Add support for StorageBuffer (#3348)

Fixes #3347.
diff --git a/source/fuzz/fuzzer_pass_donate_modules.cpp b/source/fuzz/fuzzer_pass_donate_modules.cpp
index fc71d34..b907376 100644
--- a/source/fuzz/fuzzer_pass_donate_modules.cpp
+++ b/source/fuzz/fuzzer_pass_donate_modules.cpp
@@ -125,6 +125,7 @@
     case SpvStorageClassUniformConstant:
     case SpvStorageClassPushConstant:
     case SpvStorageClassImage:
+    case SpvStorageClassStorageBuffer:
       // We change these to Private
       return SpvStorageClassPrivate;
     default: