fix misleading FATAL EXCEPTION IN SYSTEM PROCESS log

There will be the following situations about mApplicationObject：

1) fork app process will invoke ActivityThread.main(),
then set mApplicationObject.

2) fork system_server， don't set mApplicationObject value.

3) using app_process fork process except zygote, will inovke RuntimeInit,
don't set mApplicationObject value。

For example using command as below:
app_process /system/bin com.android.commands.am.Am "$@",

if this process throw uncaught exception，will output FATAL EXCEPTION IN SYSTEM PROCESS log，
it's not in system process but in normal process。

so should add condition： Process.SYSTEM_UID == Process.myUid()

BUG: 72759350
Test: manual

Change-Id: Ie8d769e4149cd9b938577058de871c4f8db9efe5
Signed-off-by: yuanhuihui <yuanhuihui@xiaomi.com>

core/java/com/android/internal/os/RuntimeInit.java

@@ -71,10 +71,11 @@ public class RuntimeInit {
         public void uncaughtException(Thread t, Throwable e) {
             // Don't re-enter if KillApplicationHandler has already run
             if (mCrashing) return;
-            if (mApplicationObject == null) {
-                // The "FATAL EXCEPTION" string is still used on Android even though
-                // apps can set a custom UncaughtExceptionHandler that renders uncaught
-                // exceptions non-fatal.
+
+            // mApplicationObject is null for non-zygote java programs (e.g. "am")
+            // There are also apps running with the system UID. We don't want the
+            // first clause in either of these two cases, only for system_server.
+            if (mApplicationObject == null && (Process.SYSTEM_UID == Process.myUid())) {
                 Clog_e(TAG, "*** FATAL EXCEPTION IN SYSTEM PROCESS: " + t.getName(), e);
             } else {
                 StringBuilder message = new StringBuilder();