Add _(darwin|linux|windows)

So that we can support building both linux and windows binaries at the
same time on a linux host. This replaces the ifeq($(HOST_OS),...) checks
in Android.mk files.

Bug: 23566667

Change-Id: I693e11984e36d55bb6f09fa0d49bc485463e16fb
diff --git a/core/base_rules.mk b/core/base_rules.mk
index b936859..3fedabc 100644
--- a/core/base_rules.mk
+++ b/core/base_rules.mk
@@ -645,9 +645,13 @@
 ALL_MODULES.$(my_register_name).PICKUP_FILES := \
     $(ALL_MODULES.$(my_register_name).PICKUP_FILES) $(LOCAL_PICKUP_FILES)
 endif
+my_required_modules := $(LOCAL_REQUIRED_MODULES) \
+    $(LOCAL_REQUIRED_MODULES_$(TARGET_$(LOCAL_2ND_ARCH_VAR_PREFIX)ARCH))
+ifdef LOCAL_IS_HOST_MODULE
+my_required_modules += $(LOCAL_REQUIRED_MODULES_$($(my_prefix)OS))
+endif
 ALL_MODULES.$(my_register_name).REQUIRED := \
-    $(strip $(ALL_MODULES.$(my_register_name).REQUIRED) $(LOCAL_REQUIRED_MODULES) \
-      $(LOCAL_REQUIRED_MODULES_$(TARGET_$(LOCAL_2ND_ARCH_VAR_PREFIX)ARCH)))
+    $(strip $(ALL_MODULES.$(my_register_name).REQUIRED) $(my_required_modules))
 ALL_MODULES.$(my_register_name).EVENT_LOG_TAGS := \
     $(ALL_MODULES.$(my_register_name).EVENT_LOG_TAGS) $(event_log_tags)
 ALL_MODULES.$(my_register_name).INTERMEDIATE_SOURCE_DIR := \
diff --git a/core/binary.mk b/core/binary.mk
index 01c8858..7b629d8 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -153,6 +153,19 @@
 endif
 endif
 
+ifdef LOCAL_IS_HOST_MODULE
+my_src_files += $(LOCAL_SRC_FILES_$($(my_prefix)OS))
+my_static_libraries += $(LOCAL_STATIC_LIBRARIES_$($(my_prefix)OS))
+my_shared_libraries += $(LOCAL_SHARED_LIBRARIES_$($(my_prefix)OS))
+my_cflags += $(LOCAL_CFLAGS_$($(my_prefix)OS))
+my_cppflags += $(LOCAL_CPPFLAGS_$($(my_prefix)OS))
+my_ldflags += $(LOCAL_LDFLAGS_$($(my_prefix)OS))
+my_ldlibs += $(LOCAL_LDLIBS_$($(my_prefix)OS))
+my_asflags += $(LOCAL_ASFLAGS_$($(my_prefix)OS))
+my_c_includes += $(LOCAL_C_INCLUDES_$($(my_prefix)OS))
+my_generated_sources += $(LOCAL_GENERATED_SOURCES_$($(my_prefix)OS))
+endif
+
 my_src_files += $(LOCAL_SRC_FILES_$($(my_prefix)$(LOCAL_2ND_ARCH_VAR_PREFIX)ARCH)) $(LOCAL_SRC_FILES_$(my_32_64_bit_suffix))
 my_shared_libraries += $(LOCAL_SHARED_LIBRARIES_$($(my_prefix)$(LOCAL_2ND_ARCH_VAR_PREFIX)ARCH)) $(LOCAL_SHARED_LIBRARIES_$(my_32_64_bit_suffix))
 my_cflags += $(LOCAL_CFLAGS_$($(my_prefix)$(LOCAL_2ND_ARCH_VAR_PREFIX)ARCH)) $(LOCAL_CFLAGS_$(my_32_64_bit_suffix))
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index c42a8e0..63ae2a2 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -255,6 +255,18 @@
 LOCAL_CLANG_$(HOST_2ND_ARCH):=
 endif
 
+LOCAL_SRC_FILES_$(HOST_OS):=
+LOCAL_STATIC_LIBRARIES_$(HOST_OS):=
+LOCAL_SHARED_LIBRARIES_$(HOST_OS):=
+LOCAL_CFLAGS_$(HOST_OS):=
+LOCAL_CPPFLAGS_$(HOST_OS):=
+LOCAL_LDFLAGS_$(HOST_OS):=
+LOCAL_LDLIBS_$(HOST_OS):=
+LOCAL_ASFLAGS_$(HOST_OS):=
+LOCAL_C_INCLUDES_$(HOST_OS):=
+LOCAL_GENERATED_SOURCES_$(HOST_OS):=
+LOCAL_REQUIRED_MODULES_$(HOST_OS):=
+
 LOCAL_SRC_FILES_32:=
 LOCAL_SRC_FILES_64:=
 LOCAL_SHARED_LIBRARIES_32:=
diff --git a/core/host_test_internal.mk b/core/host_test_internal.mk
index e0070c1..06949ed 100644
--- a/core/host_test_internal.mk
+++ b/core/host_test_internal.mk
@@ -2,12 +2,11 @@
 ## Shared definitions for all host test compilations.
 #####################################################
 
-ifeq ($(HOST_OS),windows)
-LOCAL_CFLAGS += -DGTEST_OS_WINDOWS
-else
-LOCAL_CFLAGS += -DGTEST_OS_LINUX
-LOCAL_LDLIBS += -lpthread
-endif
+LOCAL_CFLAGS_windows += -DGTEST_OS_WINDOWS
+LOCAL_CFLAGS_linux += -DGTEST_OS_LINUX
+LOCAL_LDLIBS_linux += -lpthread
+LOCAL_CFLAGS_darwin += -DGTEST_OS_LINUX
+LOCAL_LDLIBS_darwin += -lpthread
 
 LOCAL_CFLAGS += -DGTEST_HAS_STD_STRING -O0 -g
 LOCAL_C_INCLUDES +=  external/gtest/include
diff --git a/libs/host/Android.mk b/libs/host/Android.mk
index 821f9b8..8c8f755 100644
--- a/libs/host/Android.mk
+++ b/libs/host/Android.mk
@@ -1,15 +1,10 @@
 LOCAL_PATH:= $(call my-dir)
 include $(CLEAR_VARS)
-LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 
 LOCAL_SRC_FILES:= \
     CopyFile.c
 
-ifeq ($(HOST_OS),darwin)
-LOCAL_CFLAGS += -DMACOSX_RSRC
-endif
-ifeq ($(HOST_OS),linux)
-endif
+LOCAL_CFLAGS_darwin += -DMACOSX_RSRC
 
 LOCAL_MODULE:= libhost
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
diff --git a/tools/zipalign/Android.mk b/tools/zipalign/Android.mk
index 4194f81..cba6db3 100644
--- a/tools/zipalign/Android.mk
+++ b/tools/zipalign/Android.mk
@@ -22,15 +22,11 @@
 	liblog \
 	libzopfli
 
-ifeq ($(HOST_OS),linux)
-LOCAL_LDLIBS += -lrt
-endif
+LOCAL_LDLIBS_linux += -lrt
 
-ifdef USE_MINGW
-LOCAL_STATIC_LIBRARIES += libz
-else
-LOCAL_LDLIBS += -lz
-endif
+LOCAL_STATIC_LIBRARIES_windows += libz
+LOCAL_LDLIBS_linux += -lz
+LOCAL_LDLIBS_darwin += -lz
 
 ifneq ($(strip $(BUILD_HOST_static)),)
 LOCAL_LDLIBS += -lpthread