Couple libbatteryservice headers with module.

Also moved these headers to be local to the service.

Test: used headers with BOARD_VNDK_VERSION=current
Bug: 37342627
Change-Id: I1d8142ff53036e99cf509a22855928248c29a924
diff --git a/services/batteryservice/Android.bp b/services/batteryservice/Android.bp
index e441bda..4c7265b 100644
--- a/services/batteryservice/Android.bp
+++ b/services/batteryservice/Android.bp
@@ -1,3 +1,11 @@
+cc_library_headers {
+    name: "libbatteryservice_headers",
+    vendor_available: true,
+    export_include_dirs: ["include"],
+    header_libs: ["libbinder_headers"],
+    export_header_lib_headers: ["libbinder_headers"],
+}
+
 cc_library {
     name: "libbatteryservice",
 
@@ -8,6 +16,9 @@
         "IBatteryPropertiesRegistrar.cpp",
     ],
 
+    header_libs: ["libbatteryservice_headers"],
+    export_header_lib_headers: ["libbatteryservice_headers"],
+
     shared_libs: [
         "libutils",
         "libbinder",
@@ -19,4 +30,4 @@
         "-Wunused",
         "-Wunreachable-code",
     ],
-}
\ No newline at end of file
+}