Patch BUILD.bazel to support fuchsia.

This is needed for the bazel SDK.
diff --git a/BUILD.bazel b/BUILD.bazel
index b1e3b7f..84239fe 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -57,6 +57,11 @@
 )
 
 config_setting(
+    name = "fuchsia",
+    values = {"crosstool_top": "@fuchsia_clang//:toolchain"},
+)
+
+config_setting(
     name = "msvc_compiler",
     flag_values = {
         "@bazel_tools//tools/cpp:compiler": "msvc-cl",
@@ -147,6 +152,13 @@
             "@com_googlesource_code_re2//:re2",
         ],
         "//conditions:default": [],
+    }) + select({
+        ":fuchsia": [
+            "@fuchsia_sdk//pkg/fdio",
+            "@fuchsia_sdk//pkg/syslog",
+            "@fuchsia_sdk//pkg/zx",
+        ],
+        "//conditions:default": [],
     }),
 )