Fix skydoc following of nontrivial relative labels.

Previously, only trivial relative paths (within the same package) were handled correctly. Now paths such as ":foo/bar.bzl" are handled appropriately.

RELNOTES: None.
PiperOrigin-RevId: 206237161

src/test/java/com/google/devtools/build/skydoc/BUILD

diff --git a/src/test/java/com/google/devtools/build/skydoc/BUILD b/src/test/java/com/google/devtools/build/skydoc/BUILD
index f36e9db..1df4b52 100644
--- a/src/test/java/com/google/devtools/build/skydoc/BUILD
+++ b/src/test/java/com/google/devtools/build/skydoc/BUILD
@@ -8,7 +8,9 @@
 filegroup(
     name = "srcs",
     testonly = 0,
-    srcs = glob(["**"]),
+    srcs = glob(["**"]) + [
+        "//src/test/java/com/google/devtools/build/skydoc/testdata/same_level_file_test:srcs",
+    ],
     visibility = ["//src:__pkg__"],
 )
 
@@ -20,6 +22,7 @@
     visibility = ["//devtools/blaze/main:__pkg__"],
     deps = [
         "//src/main/java/com/google/devtools/build/lib:syntax",
+        "//src/main/java/com/google/devtools/build/lib/cmdline",
         "//src/main/java/com/google/devtools/build/lib/vfs",
         "//src/main/java/com/google/devtools/build/skydoc:skydoc_lib",
         "//src/main/java/com/google/devtools/build/skydoc/fakebuildapi",