[ET-VK] Support setting cache_data_path at build time (pytorch#11383)

Differential Revision: [D75708084](https://our.internmc.facebook.com/intern/diff/D75708084/)

Author: pytorchbot

backends/vulkan/runtime/vk_api/Runtime.cpp

@@ -381,7 +381,12 @@ std::string& set_and_get_pipeline_cache_data_path(
     const std::string& file_path) {
   // The global cache data path is declared as a static local variable for the
   // same reasons as the global runtime below.
+#if defined(ETVK_DEFAULT_CACHE_PATH)
+  static std::string global_cache_data_path = ETVK_DEFAULT_CACHE_PATH;
+#else
   static std::string global_cache_data_path;
+#endif /* ETVK_DEFAULT_CACHE_PATH */
+
   if (file_path.size() > 0) {
     global_cache_data_path = file_path;
   }

backends/vulkan/targets.bzl

@@ -170,6 +170,10 @@ def define_common_targets(is_fbcode = False):
                 "ovr_config//os:macos": mac_flags,
             })
 
+            etvk_default_cache_path = read_config("etvk", "default_cache_path", "")
+            if etvk_default_cache_path != "":
+                VK_API_PREPROCESSOR_FLAGS += ["-DETVK_DEFAULT_CACHE_PATH={}".format(etvk_default_cache_path)]
+
             debug_mode = read_config("etvk", "debug", "0") == "1"
             if debug_mode:
                 VK_API_PREPROCESSOR_FLAGS += ["-DVULKAN_DEBUG"]