Add elf abi to ppc64 targets

Related to the Rust 1.90.0 to "expose elf abi on ppc64 targets": rust-lang/rust#142321

Without this, build (e.g. firefox) fails on powerpc targets with the error message:

	warning: glslopt@0.1.11: clang-20: error: version 'elfv2' in target triple 'powerpc64le-alpine-linux-muslelfv2' is invalid

Closes: rust-lang#1581
Co-Authored-By: Sertonix <sertonix@posteo.net>

Author: fossdd

src/target/llvm.rs

@@ -98,6 +98,7 @@ impl TargetInfo<'_> {
             "llvm" | "softfloat" | "uwp" | "vec-extabi" => "",
             "ilp32" => "_ilp32",
             "abi64" => "",
+            "elfv1" | "elfv2" => "",
             abi => abi,
         };
         Cow::Owned(match (vendor, env, abi) {