Auto merge of #184 - servo:jdm-patch-10, r=asajeffrey

Pass correct targets for arm64 windows builds.

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Author: bors-servo

makefile.cargo

@@ -121,6 +121,9 @@ ifeq ($(findstring x86_64,$(TARGET)),x86_64)
 else ifeq ($(findstring i686,$(TARGET)),i686)
 	# This is the correct target for MSVC builds
 	CONFIGURE_FLAGS += --target=i686-pc-mingw32 --host=x86_64-pc-mingw32
+else ifeq ($(findstring aarch64,$(TARGET)),aarch64)
+	# This is the correct target for MSVC builds
+	CONFIGURE_FLAGS += --target=aarch64-windows-mingw32 --host=x86_64-pc-mingw32
 endif
 	MOZ_TOOLS=/