Add systrace tag for system property

Introduce a new systrace tag, TRACE_TAG_SYSPROP, for use with
system property.

Bug: 147275573
Test: build
Change-Id: Id78992d238a73257bb9b80bfaa6bbfeb16f477d8

core/java/android/os/Trace.java

@@ -102,6 +102,8 @@ public final class Trace {
     /** @hide */
     public static final long TRACE_TAG_RRO = 1L << 26;
     /** @hide */
+    public static final long TRACE_TAG_SYSPROP = 1L << 27;
+    /** @hide */
     public static final long TRACE_TAG_APEX_MANAGER = 1L << 18;
 
     private static final long TRACE_TAG_NOT_READY = 1L << 63;