Update bdwgc to latest unity-release-7_4 revision

lukaszunity · lukaszunity · commit 5fbf2c40e448 · 2018-05-30T09:04:27.000+02:00
diff --git a/external/bdwgc b/external/bdwgc
@@ -1 +1 @@
-Subproject commit 8440aa8cdffda0b9aa324a0e63f950f05551ab27
+Subproject commit b46167f4118a03a96bb8055639e64a9e4e73cab5
