Apply gn format with 'sources' sorting to src/

mojo/nacl/BUILD.gn

 # All toolchains use the same generated code.
 gen_dir = "$root_build_dir/gen/mojo/nacl"
 
 # Only allow the generator to be run by one toolchain.
 if (current_toolchain == default_toolchain) {
   # Generate the code to plumb the Mojo public API into the NaCl sandbox.
   action("mojo_nacl_codegen") {
     script = "generator/generate_nacl_bindings.py"
     args = [
       "-d",
@@ skipping 13 matching lines @@
       "$gen_dir/libmojo.cc",
     ]
   }
 }
 
 # Trusted code
 if (!is_nacl) {
   # A library for launching a NaCl sandbox connected to a Mojo embedder.
   static_library("monacl_sel") {
     sources = [
+      "$gen_dir/mojo_syscall.cc",
       "mojo_syscall_internal.h",
-      "$gen_dir/mojo_syscall.cc",
       "monacl_sel_main.cc",
     ]
 
     deps = [
       # This target makes sure we have all the pre-processor defines needed to
       # use NaCl's headers.
       "//native_client/build/config/nacl:nacl_base",
       "//native_client/src/trusted/desc:nrd_xfer",
       "//native_client/src/trusted/service_runtime:sel_main_chrome",
       ":mojo_nacl_codegen($default_toolchain)",
@@ skipping 27 matching lines @@
       "$gen_dir/mojo_irt.h",
     ]
     public_deps = [
       "//native_client/build/config/nacl:nacl_base",
       "//native_client/src/untrusted/irt:irt_core_lib",
       "//native_client/src/untrusted/nacl:imc_syscalls",
       ":mojo_nacl_codegen($default_toolchain)",
     ]
   }
 }