Remove the outputPath parameter from BlazeModule.getFileSystem.

It's never used, and it's tricky to run with multiple different file systems
in the same process -> remove it to simplify.

--
MOS_MIGRATED_REVID=129858142
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java b/src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java
index 851f647..eb3e6a6 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java
@@ -882,11 +882,9 @@
           "Bad --output_base option specified: '" + outputBase + "'");
     }
 
-    PathFragment outputPathFragment = BlazeDirectories.outputPathFromOutputBase(
-        outputBase, workspaceDirectory, startupOptions.deepExecRoot, productName);
     FileSystem fs = null;
     for (BlazeModule module : blazeModules) {
-      FileSystem moduleFs = module.getFileSystem(options, outputPathFragment);
+      FileSystem moduleFs = module.getFileSystem(options);
       if (moduleFs != null) {
         Preconditions.checkState(fs == null, "more than one module returns a file system");
         fs = moduleFs;