ncurses can't build with std=c23 (default with gcc 15)

Author: henderkes

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

@@ -16,6 +16,7 @@ protected function build(): void
 
         UnixAutoconfExecutor::create($this)
             ->appendEnv([
+                'CFLAGS' => '-std=gnu99',
                 'LDFLAGS' => SPCTarget::isStatic() ? '-static' : '',
             ])
             ->configure(