fix clang musl compilation

src/SPC/builder/unix/library/libedit.php

@@ -11,6 +11,7 @@ trait libedit
     protected function build(): void
     {
         UnixAutoconfExecutor::create($this)
+            ->appendEnv(['CFLAGS' => '-D__STDC_ISO_10646__=201103L'])
             ->configure()
             ->make();
         $this->patchPkgconfPrefix(['libedit.pc']);