[fuchsia] Fix Fuchsia build of swiftshader_vulkan_unittests

When building the vulkan library (libvk_swiftshader.so) for Fuchsia,
do not place the stripped binary to $OUT_DIR/swiftshader/ instead of
its default location (i.e. $OUT_DIR/lib/).

That's because the Fuchsia packaging scripts rely on the location
of the unstripped library ($OUT+DIR/lib.unstripped/) to find the
release one (i.e. by replacing 'lib.unstripped' with 'lib').

This resulted in a build error (see bug for details). This CL
works around the issue rather than fixing the scripts.

Bug chromium:1000668

Change-Id: I4137c9edbdc04b3b35a8a43e3f37b9e64fe5b1d7
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/35968
Tested-by: David Turner <digit@google.com>
Kokoro-Presubmit: David Turner <digit@google.com>
Presubmit-Ready: David Turner <digit@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
diff --git a/src/Vulkan/BUILD.gn b/src/Vulkan/BUILD.gn
index 7da1c59..23d0f03 100644
--- a/src/Vulkan/BUILD.gn
+++ b/src/Vulkan/BUILD.gn
@@ -121,7 +121,10 @@
   configs = [ ":swiftshader_libvulkan_private_config" ]
 
   output_name = "libvk_swiftshader"
-  output_dir = "$root_out_dir/swiftshader"
+  if (!is_fuchsia) {
+    # NOTE: Work-around for http://crbug.com/1000668
+    output_dir = "$root_out_dir/swiftshader"
+  }
 
   if (is_mac) {
     ldflags = [