wasm: Remove unused stdarg.h.
wasm: Remove unused stdarg.h.

This is available in clang builtin headers.

Signed-off-by: Teemu Koponen <514c492c49408016e397a2f741baa6dd9cf7f3be@styra.com>

tsandall/opa,open-policy-agent/opa,open-policy-agent/opa,tsandall/opa,open-policy-agent/opa,open-policy-agent/opa,tsandall/opa,tsandall/opa,tsandall/opa,open-policy-agent/opa,open-policy-agent/opa,tsandall/opa