Enable libevent on linux_bionic builds

Bug: 31559095
Test: Enable host bionic, run soong
Change-Id: I843c22dc2647d5c60e27812171411359486c0dce
diff --git a/Android.bp b/Android.bp
index 08a7dbb..1e7cb37 100644
--- a/Android.bp
+++ b/Android.bp
@@ -69,6 +69,10 @@
             srcs: ["epoll.c"],
             host_ldlibs: ["-lrt"],
         },
+        linux_bionic: {
+            enabled: true,
+            srcs: ["epoll.c"],
+        },
         darwin: {
             srcs: ["kqueue.c"],
         },