fixes for building with swiftpm (#225)

- clbas is part of veclib (compile failure)
- add SWIFTPM_BUNDLE #define to allow loading the metallib from a swiftpm resource bundle

mlx/backend/common/default_primitives.cpp

@@ -1,6 +1,6 @@
 // Copyright © 2023 Apple Inc.
 
-#include <cblas.h>
+#include <VecLib/cblas.h>
 
 #include "mlx/array.h"
 #include "mlx/backend/common/copy.h"

mlx/backend/metal/device.cpp

@@ -42,6 +42,25 @@ std::pair<MTL::Library*, NS::Error*> load_library_from_path(
   return std::make_pair(lib, error);
 }
 
+#ifdef SWIFTPM_BUNDLE
+MTL::Library* try_load_bundle(MTL::Device* device, NS::URL* url) {
+  std::string bundle_path = std::string(url->fileSystemRepresentation()) + "/" +
+      SWIFTPM_BUNDLE + ".bundle";
+  auto bundle = NS::Bundle::alloc()->init(
+      NS::String::string(bundle_path.c_str(), NS::UTF8StringEncoding));
+  if (bundle != nullptr) {
+    std::string resource_path =
+        std::string(bundle->resourceURL()->fileSystemRepresentation()) + "/" +
+        "default.metallib";
+    auto [lib, error] = load_library_from_path(device, resource_path.c_str());
+    if (lib) {
+      return lib;
+    }
+  }
+  return nullptr;
+}
+#endif
+
 MTL::Library* load_library(
     MTL::Device* device,
     const std::string& lib_name = "mlx",
@@ -55,6 +74,26 @@ MTL::Library* load_library(
     }
   }
 
+#ifdef SWIFTPM_BUNDLE
+  // try to load from a swiftpm resource bundle -- scan the available bundles to
+  // find one that contains the named bundle
+  {
+    MTL::Library* library =
+        try_load_bundle(device, NS::Bundle::mainBundle()->bundleURL());
+    if (library != nullptr) {
+      return library;
+    }
+    auto bundles = NS::Bundle::allBundles();
+    for (int i = 0, c = (int)bundles->count(); i < c; i++) {
+      auto bundle = reinterpret_cast<NS::Bundle*>(bundles->object(i));
+      library = try_load_bundle(device, bundle->resourceURL());
+      if (library != nullptr) {
+        return library;
+      }
+    }
+  }
+#endif
+
   // Couldn't find it so let's load it from default_mtllib_path
   {
     auto [lib, error] = load_library_from_path(device, lib_path);