[DO NOT MERGE] re-add minicore for test

Author: taiki-e

tests/ui/abi/avr-sram.rs

@@ -1,3 +1,4 @@
+//@ add-minicore
 //@ revisions: has_sram no_sram disable_sram
 //@ build-pass
 //@[has_sram] compile-flags: --target avr-none -C target-cpu=atmega328p
@@ -13,3 +14,6 @@
 #![feature(no_core)]
 #![no_core]
 #![crate_type = "lib"]
+
+extern crate minicore;
+use minicore::*;