Allow consumers to set always_include_developer_search_paths in swift…

…_library (bazel-ios#852)

bazelbuild/rules_swift#1162

rules/library.bzl

@@ -579,6 +579,7 @@ def apple_library(
     testonly = kwargs.pop("testonly", False)
     features = kwargs.pop("features", [])
     plugins = kwargs.pop("plugins", None)
+    always_include_developer_search_paths = kwargs.pop("always_include_developer_search_paths", None)
 
     for (k, v) in {"momc_copts": momc_copts, "mapc_copts": mapc_copts, "ibtool_copts": ibtool_copts}.items():
         if v:
@@ -957,8 +958,15 @@ def apple_library(
     )
 
     if swift_sources:
+        swift_kwargs = kwargs
+
         # To be backward compatible with rules_apple 2.x
-        swift_kwargs = dicts.add(kwargs, {"plugins": plugins} if plugins else {})
+        if plugins:
+            swift_kwargs = dicts.add(swift_kwargs, {"plugins": plugins})
+
+        # Allow consumers to opt-in to https://github.com/bazelbuild/rules_swift/pull/1162
+        if always_include_developer_search_paths:
+            swift_kwargs = dicts.add(swift_kwargs, {"always_include_developer_search_paths": always_include_developer_search_paths})
 
         swift_library(
             name = swift_libname,