accel/tcg: Precompute curr_cflags into cpu->tcg_cflags

The primary motivation is to remove a dozen insns along
the fast-path in tb_lookup.  As a byproduct, this allows
us to completely remove parallel_cpus.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

linux-user/main.c

@@ -205,6 +205,7 @@ CPUArchState *cpu_copy(CPUArchState *env)
     /* Reset non arch specific state */
     cpu_reset(new_cpu);
 
+    new_cpu->tcg_cflags = cpu->tcg_cflags;
     memcpy(new_env, env, sizeof(CPUArchState));
 
     /* Clone all break/watchpoints.