GN: Change rtc_source_set targets --> rtc_static_library

webrtc/system_wrappers/BUILD.gn

Index: webrtc/system_wrappers/BUILD.gn
diff --git a/webrtc/system_wrappers/BUILD.gn b/webrtc/system_wrappers/BUILD.gn
index 8087f69df79bacf7fa719642327cb864d64207e3..4dd85c24fcab2cde11884b49b477224557de09f7 100644
--- a/webrtc/system_wrappers/BUILD.gn
+++ b/webrtc/system_wrappers/BUILD.gn
@@ -12,7 +12,7 @@ if (is_android) {
 }
 import("../build/webrtc.gni")
 
-rtc_source_set("system_wrappers") {
+rtc_static_library("system_wrappers") {
   sources = [
     "include/aligned_array.h",
     "include/aligned_malloc.h",
@@ -136,21 +136,21 @@ rtc_source_set("system_wrappers") {
   deps += [ "../base:rtc_base_approved" ]
 }
 
-rtc_source_set("field_trial_default") {
+rtc_static_library("field_trial_default") {
   sources = [
     "include/field_trial_default.h",
     "source/field_trial_default.cc",
   ]
 }
 
-rtc_source_set("metrics_default") {
+rtc_static_library("metrics_default") {
   sources = [
     "include/metrics_default.h",
     "source/metrics_default.cc",
   ]
 }
 
-rtc_source_set("system_wrappers_default") {
+group("system_wrappers_default") {
   deps = [
     ":field_trial_default",
     ":metrics_default",
@@ -159,7 +159,7 @@ rtc_source_set("system_wrappers_default") {
 }
 
 if (is_android) {
-  rtc_source_set("cpu_features_android") {
+  rtc_static_library("cpu_features_android") {
     sources = [
       "source/cpu_features_android.c",
     ]
@@ -171,7 +171,7 @@ if (is_android) {
 }
 
 if (is_linux) {
-  rtc_source_set("cpu_features_linux") {
+  rtc_static_library("cpu_features_linux") {
     sources = [
       "source/cpu_features_linux.c",
     ]