Polish nanopb hack

gRPC-Core.podspec

@@ -1264,7 +1264,7 @@ Pod::Spec.new do |s|
 
   # TODO (mxyan): Instead of this hack, add include path "third_party" to C core's include path?
   s.prepare_command = <<-END_OF_COMMAND
-    find src/core/ -type f ! -path '*.grpc_back' -exec sed -E -i'.grpc_back' 's;#include "(pb(_.*)?\\.h)";#include <nanopb/\\1>;g' {} \\\;
+    find src/core/ -type f ! -path '*.grpc_back' -print0 | xargs -0 -L1 sed -E -i'.grpc_back' 's;#include "(pb(_.*)?\\.h)";#include <nanopb/\\1>;g'
-    find src/core/ -type f -path '*.grpc_back' | xargs rm
+    find src/core/ -type f -path '*.grpc_back' -print0 | xargs -0 rm
   END_OF_COMMAND
 end

templates/gRPC-Core.podspec.template

@@ -220,7 +220,7 @@
 
     # TODO (mxyan): Instead of this hack, add include path "third_party" to C core's include path?
     s.prepare_command = <<-END_OF_COMMAND
-      find src/core/ -type f ! -path '*.grpc_back' -exec sed -E -i'.grpc_back' 's;#include "(pb(_.*)?\\.h)";#include <nanopb/\\1>;g' {} \\\;
+      find src/core/ -type f ! -path '*.grpc_back' -print0 | xargs -0 -L1 sed -E -i'.grpc_back' 's;#include "(pb(_.*)?\\.h)";#include <nanopb/\\1>;g'
-      find src/core/ -type f -path '*.grpc_back' | xargs rm
+      find src/core/ -type f -path '*.grpc_back' -print0 | xargs -0 rm
     END_OF_COMMAND
   end