Remove unnecessary getpriority() system call

This was introduced for a valid reason in aosp/1224543, but that reason
was later removed. This code wasn't.

It is not worth making a system call in order to possibly avoid a second
one, which I expect is no more expensive in that, particularly easy,
case.

Test: Treehugger
Change-Id: I346f9b641c6feb791247b16fb900a4ad97e646d2
diff --git a/libutils/Threads.cpp b/libutils/Threads.cpp
index d8d75ac..111d46a 100644
--- a/libutils/Threads.cpp
+++ b/libutils/Threads.cpp
@@ -313,11 +313,6 @@
 int androidSetThreadPriority(pid_t tid, int pri)
 {
     int rc = 0;
-    int curr_pri = getpriority(PRIO_PROCESS, tid);
-
-    if (curr_pri == pri) {
-        return rc;
-    }
 
     if (setpriority(PRIO_PROCESS, tid, pri) < 0) {
         rc = INVALID_OPERATION;