use of ifndef inhibit_libc to disable the contents linux-unwind.h for targets with MD_UNWIND_SUPPORT

[Stephen M. Kenton]

David Daney wrote:
> You never state what you are trying to build.  "cross compiler" does 
> not really narrow it down.
>
> Also you don't state what errors you are experiencing.
I'm experimenting with building a Linux based cross compiler/tool-chain 
for building the Kernel and Apps
for every target in the kernel/arch directory.  Following various sets 
of instructions I can just about do that,
but the question arose in my mind, why, after reading the documentation 
and some research, that doing
the obvious configure/make/install fails in so many cases.  In this 
particular subset of failures involving
inhibit_libc, MD_UNWIND_SUPPORT and linux-unwind.h the problem is 
attempting to include
files which are not available.  I know how to work around it, but it 
seems like something should be
fixed so that other people won't have to work around it.  Things should 
just work.  Hence my question below.
>
>> Is there some reason that every instance of linux-unwind.h should not 
>> start and end with those same
>> #ifndef inhibit_libc ... #endif  statements?
>
> In the case of mips, I believe that  inhibit_libc is a surrogate for a 
> check that signal.h and asm/unistd.h are usable.
Exactly.  Except for mips and i386, the compile fails with a "missing 
file" error if inhbit_libc is set in this situation.

I hacked up a few of the other linux-unwind.h files and alpha just 
finished successfully.

Steve