[PATCH, Makefile] improve libsubdir variable transmission to sub-makes on Windows

[Jeff Law]

On 09/01/2017 02:42 AM, Olivier Hainque wrote:
> Hello,
> 
> To convey the value of libsubdir to sub-makes, gcc/Makefile.in has
> 
>   # Flags to pass to recursive makes.
>   # CC is set by configure.
>   # ??? The choices here will need some experimenting with.
> 
>   export AR_FOR_TARGET
>   ...
>   export libsubdir
> 
> then:
> 
>   FLAGS_TO_PASS = \
>   ...
>   (libsubdir not here)
> 
> This is not working well on cygwin environments where environment
> variable names are translated to uppercase (so sub-makes evaluating
> the variable with the lowercase name don't get the value).
> 
> The attached patch is a suggestion to address this by simply adding
> "libsubdir" to the list of explicit FLAGS_TO_PASS.
> 
> Used in-house for a while, with gcc-6 on a wide variety of host/target
> configurations.
> 
> Bootstrapped and regression tested with mainline on x86_64-linux.
> 
> OK to commit ?
> 
> Thanks in advance,
> 
> With Kind Regards,
> 
> Olivier
> 
> 2017-09-01  Jerome Lambourg  <lambourg@adacore.com>
> 
> 	* Makefile.in (FLAGS_TO_PASS): Add libsubdir.
OK.

Jeff