Unrolled build for #142680

Rollup merge of #142680 - beetrees:sparc64-float-struct-abi, r=tgross35

Fix passing/returning structs with the 64-bit SPARC ABI

Fixes the 64-bit SPARC part of #115609 by replacing the current implementation with a new implementation modelled on the RISC-V calling convention code ([SPARC ABI reference](https://sparc.org/wp-content/uploads/2014/01/SCD.2.4.1.pdf.gz)).

Pinging `sparcv9-sun-solaris` target maintainers: @psumbera @kulikjak
Fixes #115336
Fixes #115399
Fixes #122620
Fixes #147883
r? @workingjubilee

Author: rust-timer

compiler/rustc_abi/src/callconv/reg.rs

@@ -35,6 +35,7 @@ impl Reg {
 
     reg_ctor!(f32, Float, 32);
     reg_ctor!(f64, Float, 64);
+    reg_ctor!(f128, Float, 128);
 }
 
 impl Reg {