radeonsi/gfx10: move s_sendmsg gs_alloc_req to the beginning of shaders

This will allow us to merge some IF blocks in shaders.

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>

src/gallium/drivers/radeonsi/si_shader_internal.h

@@ -299,6 +299,7 @@ void si_llvm_emit_streamout(struct si_shader_context *ctx,
 			    unsigned noutput, unsigned stream);
 void si_create_function(struct si_shader_context *ctx);
 
+void gfx10_ngg_build_sendmsg_gs_alloc_req(struct si_shader_context *ctx);
 void gfx10_emit_ngg_epilogue(struct ac_shader_abi *abi,
 			     unsigned max_outputs,
 			     LLVMValueRef *addrs);