Use avr-gcc's bitshift implementations

rust-lang/rust#82242 (comment)

Author: gergoerdi

src/int/shift.rs

@@ -70,46 +70,55 @@ impl Lshr for u128 {}
 
 intrinsics! {
     #[maybe_use_optimized_c_shim]
+    #[avr_skip]
     pub extern "C" fn __ashlsi3(a: u32, b: u32) -> u32 {
         a.ashl(b)
     }
 
     #[maybe_use_optimized_c_shim]
     #[arm_aeabi_alias = __aeabi_llsl]
+    #[avr_skip]
     pub extern "C" fn __ashldi3(a: u64, b: u32) -> u64 {
         a.ashl(b)
     }
 
+    #[avr_skip]
     pub extern "C" fn __ashlti3(a: u128, b: u32) -> u128 {
         a.ashl(b)
     }
 
     #[maybe_use_optimized_c_shim]
+    #[avr_skip]
     pub extern "C" fn __ashrsi3(a: i32, b: u32) -> i32 {
         a.ashr(b)
     }
 
     #[maybe_use_optimized_c_shim]
     #[arm_aeabi_alias = __aeabi_lasr]
+    #[avr_skip]
     pub extern "C" fn __ashrdi3(a: i64, b: u32) -> i64 {
         a.ashr(b)
     }
 
+    #[avr_skip]
     pub extern "C" fn __ashrti3(a: i128, b: u32) -> i128 {
         a.ashr(b)
     }
 
     #[maybe_use_optimized_c_shim]
+    #[avr_skip]
     pub extern "C" fn __lshrsi3(a: u32, b: u32) -> u32 {
         a.lshr(b)
     }
 
     #[maybe_use_optimized_c_shim]
     #[arm_aeabi_alias = __aeabi_llsr]
+    #[avr_skip]
     pub extern "C" fn __lshrdi3(a: u64, b: u32) -> u64 {
         a.lshr(b)
     }
 
+    #[avr_skip]
     pub extern "C" fn __lshrti3(a: u128, b: u32) -> u128 {
         a.lshr(b)
     }