Move libandroid_net from Android.mk to Android.bp.

This is the first step of making libandroid_net available to
vendor code. This is a partial cherry-pick of ag/2210044 that
only moves the build target (hence the Merged-In change ID).

Bug: 37527489
Test: marlin builds and boots
Change-Id: Id9e4d13d4e75f6f6381c675c4e9f72e9f4769d22
Merged-In: Ie3c9c3d3c8c75ade36422d1e8ee0a5fe117e9091

native/android/Android.bp

@@ -19,3 +19,24 @@ ndk_library {
     first_version: "9",
     unversioned_until: "current",
 }
+
+cc_defaults {
+    name: "libandroid_defaults",
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wunused",
+        "-Wunreachable-code",
+    ],
+}
+
+// Network library.
+cc_library_shared {
+    name: "libandroid_net",
+    defaults: ["libandroid_defaults"],
+    srcs: ["net.c"],
+
+    shared_libs: ["libnetd_client"],
+
+    include_dirs: ["bionic/libc/dns/include"],
+}

native/android/Android.mk

@@ -58,20 +58,3 @@ LOCAL_MODULE := libandroid
 LOCAL_CFLAGS += $(common_cflags)
 
 include $(BUILD_SHARED_LIBRARY)
-
-# Network library.
-include $(CLEAR_VARS)
-LOCAL_MODULE := libandroid_net
-LOCAL_CFLAGS := $(common_cflags)
-LOCAL_SRC_FILES:= \
-    net.c \
-
-LOCAL_SHARED_LIBRARIES := \
-    libnetd_client \
-
-LOCAL_C_INCLUDES += \
-    frameworks/base/native/include \
-    bionic/libc/dns/include \
-    system/netd/include \
-
-include $(BUILD_SHARED_LIBRARY)