[patch,lto] Fix PR81487

[Georg-Johann Lay]

Hi, this patch fixes some minor problems in lto-plugin:

Some older mingw32 host environments have broken asprintf.
As far as I can tell, the problem is that the mingw asprintf
implementation calls _vsnprintf (NULL, 0, ...) which always
returns -1 as length on the host.

The patch fixes this by using xasprintf from libiberty with
the additional benefit of easier use and unified error reporting
in the case when there is actually no more memory available, i.e.
it will use the same error massages like xmalloc then.

Moreover, the old implementation calls asprintf as

 > asprintf (&objname, "%s@0x%x%08x", file->name, lo, hi)

for large archives when the high 32 bits (hi) are non-zero.
This looks like a typo: the high part must come first to yiels
a proper 64-bit value.

Bootstrapped & re-tested on x86_64-linux gnu and also on
mingw32 which popped the "ld.exe: asprintf failed".

Ok for trunk?

Johann


lto-plugin/
	PR lto/81487
	* lto-plugin.c (claim_file_handler): Use xasprintf instead of
	asprintf.
	[hi!=0]: Swap hi and lo arguments supplied to xasprintf.
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