Change some source_sets to static_library to shrink binary

src/trusted/service_runtime/BUILD.gn

 # Copyright (c) 2014 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/toolchain/toolchain.gni")
 import("//native_client/src/trusted/asm.gni")
 
 source_set("sel_main") {
   sources = [
     "sel_main.c",
   ]
   deps = [
     "//build/config/nacl:nacl_base",
     "//native_client/src/trusted/debug_stub:debug_stub",
     ":sel",
   ]
 }
 
-source_set("sel_main_chrome") {
+static_library("sel_main_chrome") {
   sources = [
     "sel_main_chrome.c",
   ]
   deps = [
     "//build/config/nacl:nacl_base",
     "//native_client/src/trusted/debug_stub:debug_stub",
     ":sel",
   ]
 }
 
@@ skipping 51 matching lines @@
         "arch/mips/nacl_syscall.S",
         "arch/mips/tramp_mips.S",
       ]
     }
     deps = [
       "//build/config/nacl:nacl_base",
     ]
   }
 }
 
-source_set("sel") {
+static_library("sel") {
   sources = [
     "dyn_array.c",
     "elf_util.c",
     "filename_util.cc",
     "load_file.c",
     "nacl_all_modules.c",
     "nacl_app_thread.c",
     "nacl_copy.c",
     "nacl_desc_effector_ldr.c",
     "nacl_error_gio.c",
@@ skipping 248 matching lines @@
     configs -= [ "//build/config:default_libs" ]
     libs = [ "rt" ]
     ldflags = [ "-pie" ]
   }
   if (is_linux) {
     data_deps = [
       "linux:bootstrap",
     ]
   }
 }