target-i386: fix compilation with --enable-debug-tcg

Commit 2355c16e introduced a new ldmxcsr
helper taking an i32 argument, but the helper is actually passed a long.
Fix that by truncating the long to i32.
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

target-i386/translate.c

@@ -7544,7 +7544,8 @@ static target_ulong disas_insn(DisasContext *s, target_ulong pc_start)
             gen_lea_modrm(s, modrm, &reg_addr, &offset_addr);
             if (op == 2) {
                 gen_op_ld_T0_A0(OT_LONG + s->mem_index);
-                gen_helper_ldmxcsr(cpu_T[0]);
+                tcg_gen_trunc_tl_i32(cpu_tmp2_i32, cpu_T[0]);
+                gen_helper_ldmxcsr(cpu_tmp2_i32);
             } else {
                 tcg_gen_ld32u_tl(cpu_T[0], cpu_env, offsetof(CPUX86State, mxcsr));
                 gen_op_st_T0_A0(OT_LONG + s->mem_index);