Workaround gc crash on Windows

config.nims

@@ -1,5 +1,6 @@
 #[
-see D20190127T231316 workaround for fact that toast needs to build scanner.cc, which would otherwise result in link erros such as:
+see D20190127T231316 workaround for fact that toast needs to build
+scanner.cc, which would otherwise result in link errors such as:
 "std::terminate()", referenced from:
       ___clang_call_terminate in scanner.cc.o
 ]#
@@ -7,3 +8,7 @@ when defined(MacOSX):
   switch("clang.linkerexe", "g++")
 else:
   switch("gcc.linkerexe", "g++")
+
+# Workaround for NilAccessError crash on Windows
+when defined(Windows):
+  switch("gc", "markAndSweep")

nimterop/types.nim

@@ -76,5 +76,4 @@ template defineEnum*(typ: untyped) =
   proc `mod`*(x: int, y: typ): typ {.borrow.}
   proc `mod`*(x, y: typ): typ {.borrow.}
 
-
   proc `$` *(x: typ): string {.borrow.}