tcg: Re-order tcg_region_init vs tcg_prologue_init

Instead of delaying tcg_region_init until after tcg_prologue_init
is complete, do tcg_region_init first and let tcg_prologue_init
shrink the first region by the size of the generated prologue.

Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

bsd-user/main.c

@@ -879,7 +879,6 @@ int main(int argc, char **argv)
      * the real value of GUEST_BASE into account.
      */
     tcg_prologue_init(tcg_ctx);
-    tcg_region_init();
 
     /* build Task State */
     memset(ts, 0, sizeof(TaskState));