gn2bp: Set the output name for libcronet.so

.so file name needs to match with CronetLibraryLoader.java
(e.g. libcronet.109.0.5386.0.so)

Test: m, atest CtsCronetTestCases
Change-Id: I82285c32e82fc27ba5233e1bef7195ec57c35bea
diff --git a/tools/gn2bp/Android.bp.swp b/tools/gn2bp/Android.bp.swp
index 4626ef6..0ec99bd 100644
--- a/tools/gn2bp/Android.bp.swp
+++ b/tools/gn2bp/Android.bp.swp
@@ -6618,6 +6618,7 @@
     linker_scripts: [
         "base/android/library_loader/anchor_functions.lds",
     ],
+    stem: "libcronet.109.0.5386.0",
     target: {
         android_arm: {
             generated_headers: [