mesa uses alloca() in shader_query.cpp (and elsewhere) without including
<alloca.h>; on Redox stdlib.h does not pull it in, so the C++ compile failed
with "alloca was not declared in this scope". Redox relibc DOES provide alloca
(alloca.h = #define alloca(s) __builtin_alloca(s)); force-include it via meson
c_args/cpp_args so every alloca user resolves to the builtin. Next Redox mesa
port gap after the EGL gate; mesa now compiles past it.
vasilito
3de4a53b61