GCC 8 Ada bootstrap failure on mingw-w64

[Liu Hao]

It has been long since this was reported. Today Alexey said he had found 
the reason. He believed that 899af040b0 was causing the failure [1]. 
After reverting it the x64 bootstrap succeeded, however the x86 
bootstrap failed with an ICE [2].

So now we have two issues here. Should we file a new PR for the first 
one? It seems a regression however. I am not familiar with Ada so I am 
looking forward to your help. Thanks.

[1] 
https://github.com/Alexpux/MINGW-packages/pull/3877#issuecomment-408651809
[2] 
https://github.com/Alexpux/MINGW-packages/pull/3877#issuecomment-408667559


-- 
Best regards,
LH_Mouse