[breaking change] remove getdtablesize - removed in Android API 21

src/unix/notbsd/android/mod.rs

@@ -2070,7 +2070,6 @@ extern {
     pub fn sigaltstack(ss: *const stack_t,
                        oss: *mut stack_t) -> ::c_int;
     pub fn sem_close(sem: *mut sem_t) -> ::c_int;
-    pub fn getdtablesize() -> ::c_int;
     #[cfg_attr(target_os = "solaris", link_name = "__posix_getgrnam_r")]
     pub fn getgrnam_r(name: *const ::c_char,
                       grp: *mut ::group,