Add -DWIN32_LEAN_AND_MEAN build flag to get rid of winsock2.h warnings

It's better practice to include the minimal set of windows APIs anyways
and we're not doing anything that requires more.

Change-Id: I1b4362be4f707738b9cfbd6a87caabff8b8409ac
diff --git a/core/combo/HOST_windows-x86.mk b/core/combo/HOST_windows-x86.mk
index fdb72a7..00e1974 100644
--- a/core/combo/HOST_windows-x86.mk
+++ b/core/combo/HOST_windows-x86.mk
@@ -27,7 +27,7 @@
 ifneq ($(strip $(USE_MINGW)),)
 HOST_ACP_UNAVAILABLE := true
 TOOLS_EXE_SUFFIX :=
-$(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -DUSE_MINGW
+$(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -DUSE_MINGW -DWIN32_LEAN_AND_MEAN
 $(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -Wno-unused-parameter
 $(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += --sysroot=prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/x86_64-w64-mingw32
 $(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -m32