Auto merge of #135763 - nikic:llvm-20, r=<try>

Update to LLVM 20

LLVM 20 GA is scheduled for March 11th. Rust 1.86 will be stable on April 3rd.

* [x] #135764
* [x] #136134
* [x] rust-lang/compiler-builtins#752
* [ ] Update compiler-builtins

Tested: arm-android, test-various, x86_64-rust-for-linux, x86_64-fuchsia, dist-various-1, dist-various-2, dist-s390x-linux, dist-riscv64-linux, dist-loongarch64-musl

try-job: i686-mingw
try-job: x86_64-mingw-1
try-job: x86_64-mingw-2
try-job: dist-i686-mingw
try-job: dist-x86_64-mingw

Author: bors

src/llvm-project

@@ -242,7 +242,7 @@ pub unsafe extern "ptx-kernel" fn f_float_array_arg(_a: [f32; 5]) {}
 //pub unsafe extern "ptx-kernel" fn f_u128_array_arg(_a: [u128; 5]) {}
 
 // CHECK: .visible .entry f_u32_slice_arg(
-// CHECK: .param .u64 f_u32_slice_arg_param_0
+// CHECK: .param .u64 {{(\.ptr \.align 4 )?}}f_u32_slice_arg_param_0
 // CHECK: .param .u64 f_u32_slice_arg_param_1
 #[no_mangle]
 pub unsafe extern "ptx-kernel" fn f_u32_slice_arg(_a: &[u32]) {}