Add 64-bit windows cross-compiles

This is mostly the same as the existing 2ND_HOST / HOST_CROSS support.

The interesting thing I did here was make x86 the 'first' architecture,
and x86_64 the second. This way LOCAL_MULTILIB := first defaults to
32-bit windows modules.

  windows-x86/bin   <- defaults to 32-bit executables
  windows-x86/lib   <- 32-bit libraries, like before
  windows-x86/lib64 <- 64-bit libraries
  windows-x86/obj   <- 32-bit intermediates
  windows-x86/obj64 <- 64-bit intermediates

Then modules are registered with the names:

  host_cross_liblog    <- 32-bit, like before
  host_cross_liblog_64 <- 64-bit

Bug: 26957718
Change-Id: I9f119411acb43e973ec1e6bca3c1dc291c91556c
diff --git a/core/envsetup.mk b/core/envsetup.mk
index 46c1463..ae63ae7 100644
--- a/core/envsetup.mk
+++ b/core/envsetup.mk
@@ -62,6 +62,7 @@
 ifeq ($(HOST_OS),linux)
 HOST_CROSS_OS := windows
 HOST_CROSS_ARCH := x86
+HOST_CROSS_2ND_ARCH := x86_64
 endif
 
 ifeq ($(HOST_OS),)
@@ -276,6 +277,14 @@
 HOST_LIBRARY_PATH := $(HOST_OUT_SHARED_LIBRARIES)
 endif
 
+# Out for HOST_CROSS_2ND_ARCH
+HOST_CROSS_2ND_ARCH_VAR_PREFIX := 2ND_
+HOST_CROSS_2ND_ARCH_MODULE_SUFFIX := _64
+$(HOST_CROSS_2ND_ARCH_VAR_PREFIX)HOST_CROSS_OUT_INTERMEDIATES := $(HOST_CROSS_OUT)/obj64
+$(HOST_CROSS_2ND_ARCH_VAR_PREFIX)HOST_CROSS_OUT_INTERMEDIATE_LIBRARIES := $($(HOST_CROSS_2ND_ARCH_VAR_PREFIX)HOST_CROSS_OUT_INTERMEDIATES)/lib
+$(HOST_CROSS_2ND_ARCH_VAR_PREFIX)HOST_CROSS_OUT_SHARED_LIBRARIES := $(HOST_CROSS_OUT)/lib64
+$(HOST_CROSS_2ND_ARCH_VAR_PREFIX)HOST_CROSS_OUT_EXECUTABLES := $(HOST_CROSS_OUT_EXECUTABLES)
+
 TARGET_OUT_INTERMEDIATES := $(PRODUCT_OUT)/obj
 TARGET_OUT_HEADERS := $(TARGET_OUT_INTERMEDIATES)/include
 TARGET_OUT_INTERMEDIATE_LIBRARIES := $(TARGET_OUT_INTERMEDIATES)/lib