Inline hot path of slot_getsomeattrs().

This yields a minor speedup, which roughly balances the loss from the
upcoming introduction of callbacks to do some operations on slots.

Author: Andres Freund
Discussion: https://postgr.es/m/20181105210039.hh4vvi4vwoq5ba2q@alap3.anarazel.de

src/backend/jit/llvm/llvmjit_expr.c

@@ -345,7 +345,7 @@ llvm_compile_expr(ExprState *state)
 						params[1] = l_int32_const(op->d.fetch.last_var);
 
 						LLVMBuildCall(b,
-									  llvm_get_decl(mod, FuncSlotGetsomeattrs),
+									  llvm_get_decl(mod, FuncSlotGetsomeattrsInt),
 									  params, lengthof(params), "");
 					}