Keep a copy of curinterp on stack.
Keep a copy of curinterp on stack.

Without NO_GET_CONTEXT a threaded perl would do TLS lookup every time a
perl function or macro is called to get pointer to current context.
When NO_GET_CONTEXT is defined, Perl expects to find this pointer in a
local variable, which dTHX macro declares and initializes.

gonzus/http-nghttp2,gonzus/http-nghttp2,gonzus/http-nghttp2