check-include-order.py: Don't error out on git message utf-8 decode

Just use replacement char for undecodable values.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I3a5b9844db9158749cfad7e0a352969263e2bc96
diff --git a/script/static-checks/check-include-order.py b/script/static-checks/check-include-order.py
index e6dbec1..4b0d19d 100755
--- a/script/static-checks/check-include-order.py
+++ b/script/static-checks/check-include-order.py
@@ -173,7 +173,7 @@
     if gitlog.returncode != 0:
         return False
 
-    gitlines = gitlog.stdout.decode("utf-8").splitlines()
+    gitlines = gitlog.stdout.decode("utf-8", "replace").splitlines()
     all_files_correct = True
     for commit, comlines in group_commits(gitlines):
         for path, lines in group_files(comlines):