Incorrect getrandom() system call for PowerPC Linux

Michael Ellerman pointed out that the system call for getrandom()
on PowerPC Linux is incorrect. This bug was in the powerpc32 port,
and was carried over to the powerpc64 port too.

Author: antonblanchard

src/libstd/rand/os.rs

@@ -38,9 +38,11 @@ mod imp {
         const NR_GETRANDOM: libc::c_long = 318;
         #[cfg(target_arch = "x86")]
         const NR_GETRANDOM: libc::c_long = 355;
-        #[cfg(any(target_arch = "arm", target_arch = "powerpc",
-                  target_arch = "powerpc64", target_arch = "powerpc64le"))]
+        #[cfg(target_arch = "arm")]
         const NR_GETRANDOM: libc::c_long = 384;
+        #[cfg(any(target_arch = "powerpc", target_arch = "powerpc64",
+                  target_arch = "powerpc64le"))]
+        const NR_GETRANDOM: libc::c_long = 359;
         #[cfg(target_arch = "aarch64")]
         const NR_GETRANDOM: libc::c_long = 278;