Upgrade libgc to 8.0 release

sjoelund · OpenModelica-Hudson · commit 6571fe8922f7 · 2018-10-28T18:16:27.000+01:00
This fixes a problem with docker builds on 32-bit Linux. Belonging to [master]: - #2744
diff --git a/3rdParty b/3rdParty
@@ -1 +1 @@
-Subproject commit 9680bcc4f78eaca398941bac019eb7c24ba848f5
+Subproject commit 73168676a2d61aa4fb2077c4c9e4eb6cc4bce489
