Fix implementation of getpriority

getpriority on dietlibc is broken, doesn't return correct values or treats
properly return code from getpriority system call (see getpriority manpage and
glibc implementation for reference). This patch fixes the issue.

After applying the patch below, x86_64/getpriority.S must be removed by hand,
as patch removes everything but keeps empty file.

diff -p -up dietlibc-0.32-20090113/lib/__getpriority.c.orig dietlibc-0.32-20090113/lib/__getpriority.c
--- dietlibc-0.32-20090113/lib/__getpriority.c.orig	2009-10-09 00:23:16.000000000 -0300
+++ dietlibc-0.32-20090113/lib/__getpriority.c	2009-10-09 00:31:29.000000000 -0300
@@ -0,0 +1,12 @@
+#include <sys/resource.h>
+
+extern int __syscall_getpriority(int which, int who);
+
+int getpriority(int which, int who) {
+	int r;
+
+	r = __syscall_getpriority(which, who);
+	if (r >= 0)
+		r = 20 - r;
+	return r;
+}
diff -p -up dietlibc-0.32-20090113/syscalls.s/getpriority.S.orig dietlibc-0.32-20090113/syscalls.s/getpriority.S
--- dietlibc-0.32-20090113/syscalls.s/getpriority.S.orig	2009-10-09 00:20:55.000000000 -0300
+++ dietlibc-0.32-20090113/syscalls.s/getpriority.S	2009-10-09 00:22:43.000000000 -0300
@@ -1,3 +1,3 @@
 #include "syscalls.h"
 
-syscall(getpriority,getpriority)
+syscall(getpriority,__syscall_getpriority)
diff -p -up dietlibc-0.32-20090113/x86_64/getpriority.S.orig dietlibc-0.32-20090113/x86_64/getpriority.S
--- dietlibc-0.32-20090113/x86_64/getpriority.S.orig	2007-03-26 00:06:59.000000000 -0300
+++ dietlibc-0.32-20090113/x86_64/getpriority.S	2009-10-09 00:32:47.000000000 -0300
@@ -1,12 +0,0 @@
-#include "syscalls.h"
-
-.text
-.global getpriority
-.type   getpriority,@function
-getpriority:
-     mov     $__NR_getpriority,%al
-     xorq    %rsi,%rsi
-     call    __unified_syscall
-     neg     %rax    /* the value is bios by 20 to avoid negative values */
-     add     $20,%rax
-     ret