Fix up dirsync + enable_static_variant combo

Reviewed By: mzlee

Differential Revision: D93074586

fbshipit-source-id: 8eaf5a40b8eead1fff0b891bbf5d574101a980b4

Author: snarkmaster

folly/coro/safe/BUCK

@@ -38,6 +38,7 @@ fb_dirsync_cpp_library(
 fb_dirsync_cpp_library(
     name = "now_task",
     headers = ["NowTask.h"],
+    enable_static_variant = True,
     exported_deps = [
         "//folly/coro:task_wrapper",
         "//folly/lang:safe_alias_fwd",
@@ -47,6 +48,7 @@ fb_dirsync_cpp_library(
 fb_dirsync_cpp_library(
     name = "safe_task",
     headers = ["SafeTask.h"],
+    enable_static_variant = True,
     exported_deps = [
         ":now_task",
         "//folly/coro:task_wrapper",