Disable pthread_setschedprio for android

Author: Victor Polevoy

src/unix/notbsd/mod.rs

@@ -962,6 +962,7 @@ extern {
                                        pshared: ::c_int) -> ::c_int;
     pub fn pthread_condattr_getpshared(attr: *const pthread_condattr_t,
                                        pshared: *mut ::c_int) -> ::c_int;
+    #[cfg(not(target_os = "android"))]
     pub fn pthread_setschedprio(native: ::pthread_t,
                                 priority: ::c_int) -> ::c_int;
     pub fn pthread_getschedparam(native: ::pthread_t,