build(deps): bump third_party/prjxray from 895c280 to 3749dc6

dependabot-preview[bot] · web-flow · commit eea3dce32d50 · 2020-04-30T06:31:47.000Z
Bumps [third_party/prjxray](https://github.com/SymbiFlow/prjxray) from `895c280` to `3749dc6`. - [Release notes](https://github.com/SymbiFlow/prjxray/releases) - [Commits](f4pga/prjxray@895c280...3749dc6) Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
diff --git a/third_party/prjxray b/third_party/prjxray
@@ -1 +1 @@
-Subproject commit 895c2809090269418afecba9db9e602e4bd55aa9
+Subproject commit 3749dc63c490e0064f243d4289e50ff72cbd83ad
