[AVR] Rename the 'none_base' target spec module to 'freestanding_base'

src/librustc_target/spec/avr_unknown_unknown.rs

@@ -12,6 +12,6 @@ pub fn target() -> TargetResult {
         target_env: "".to_string(),
         target_vendor: "unknown".to_string(),
         target_c_int_width: 16.to_string(),
-        options: super::none_base::opts(),
+        options: super::freestanding_base::opts(),
     })
 }

src/librustc_target/spec/mod.rs

@@ -54,6 +54,7 @@ mod arm_base;
 mod cloudabi_base;
 mod dragonfly_base;
 mod freebsd_base;
+mod freestanding_base;
 mod fuchsia_base;
 mod haiku_base;
 mod hermit_base;
@@ -65,7 +66,6 @@ mod linux_kernel_base;
 mod linux_musl_base;
 mod msvc_base;
 mod netbsd_base;
-mod none_base;
 mod openbsd_base;
 mod redox_base;
 mod riscv_base;