Automatically export bootclasspath_fragment stubs from sdk

This change makes the tag that is used to add dependencies onto stubs
from the bootclaspath_fragment module cause the dependency to be
automatically exported from the sdk. If the dependency is a
java_sdk_library then it will be as if it was added to the
java_sdk_libs property, otherwise it will be as if it was added to the
java_header_libs property instead.

Bug: 177892522
Test: m nothing
Change-Id: I97010c4342dd39415dba81a4395db7831410436e
diff --git a/java/sdk_library.go b/java/sdk_library.go
index 05ce97a..fcc105d 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -339,12 +339,7 @@
 	})
 
 	// Register sdk member types.
-	android.RegisterSdkMemberType(&sdkLibrarySdkMemberType{
-		android.SdkMemberTypeBase{
-			PropertyName: "java_sdk_libs",
-			SupportsSdk:  true,
-		},
-	})
+	android.RegisterSdkMemberType(javaSdkLibrarySdkMemberType)
 }
 
 func RegisterSdkLibraryBuildComponents(ctx android.RegistrationContext) {
@@ -2377,6 +2372,13 @@
 	return &sdkLibrarySdkMemberProperties{}
 }
 
+var javaSdkLibrarySdkMemberType = &sdkLibrarySdkMemberType{
+	android.SdkMemberTypeBase{
+		PropertyName: "java_sdk_libs",
+		SupportsSdk:  true,
+	},
+}
+
 type sdkLibrarySdkMemberProperties struct {
 	android.SdkMemberPropertiesBase