Fix Android build issues and gRPC LB policy

templates/BUILD.gn.template

Index: templates/BUILD.gn.template
diff --git a/templates/BUILD.gn.template b/templates/BUILD.gn.template
index 81678ea97ca863afb8e650e8eb3e90947680722f..71607a21a9d98f44bf8574470a3f4c5c3562467d 100644
--- a/templates/BUILD.gn.template
+++ b/templates/BUILD.gn.template
@@ -5,6 +5,11 @@
   # Please look at the templates directory instead.
   # This file can be regenerated from the template by running
   # tools/buildgen/generate_projects.sh
+  if (is_android) {
+    import("//build/config/android/config.gni")
+    import("//build/config/android/rules.gni")
+  }
+  
   config("grpc_config") {
     include_dirs = [
       ".",
@@ -20,6 +25,14 @@
       # https://crbug.com/593874
       "GRPC_CXX0X_NO_THREAD",
     ]
+    
+    cflags_c = [
+      "-std=c99"
+    ]
+    
+    if (is_android) {
+      libs = [ "log" ] # For __android_log_write
+    }  
   }
 
   <%!