deps: sync with latest deps

The package `compiler_rt` is now a required depenency.

Signed-off-by: Sean Cross <sean@xobs.io>

.gitmodules

@@ -19,3 +19,6 @@
 [submodule "hw/deps/spibone"]
 	path = hw/deps/spibone
 	url = https://github.com/xobs/spibone.git
+[submodule "hw/deps/pythondata-software-compiler_rt"]
+	path = hw/deps/pythondata-software-compiler_rt
+	url = https://github.com/litex-hub/pythondata-software-compiler_rt.git

hw/deps/litex-boards

@@ -1 +1 @@
-Subproject commit 74a5ffb9ef43c6b5e6d6d0a82d6422fb14cec9b3
+Subproject commit 2213d73b899e64707c71c87b2d79eef892018bdd

hw/deps/migen

@@ -1 +1 @@
-Subproject commit d11565a8ead28eb5a18d7d4f57abe2a7562cdc8c
+Subproject commit 5b5e4fdee19c4059b61371c6b70ae927980c24ad

hw/deps/pythondata-software-compiler_rt

@@ -0,0 +1 @@
+Subproject commit 335007c87f7fc900147b7323c9702698caa35d11

hw/deps/valentyusb

@@ -1 +1 @@
-Subproject commit a0526ad053c394306ad7a585a7ddd463831ad09d
+Subproject commit 9062a2923ce354bcfb9614f5b186e891efe69acd

hw/lxbuildenv.py

@@ -3,7 +3,7 @@
 # This script enables easy, cross-platform building without the need
 # to install third-party Python modules.
 
-LXBUILDENV_VERSION = '2020.2.18.1'
+LXBUILDENV_VERSION = '2020.4.28.1'
 import sys
 import os
 import subprocess
@@ -267,6 +267,10 @@ def check_module_recursive(root_path, depth, verbose=False, breadcrumbs=[]):
         print('git-dep: checking if "{}" requires updating (depth: {})...'.format(root_path, depth))
 
     # If the directory isn't a valid git repo, initialization is required
+    if not os.path.exists(root_path):
+        if verbose:
+            print('git-dep: subdirectory {} does not exist, so starting update'.format(root_path))
+        return True
     git_dir_cmd = subprocess.Popen(["git", "rev-parse", "--show-toplevel"],
                         cwd=root_path,
                         stdout=subprocess.PIPE,