[PATCH v2] Only build libm with -fno-math-errno

[Joseph Myers]

On Sat, 22 Dec 2018, Aurelien Jarno wrote:

> v1 -> v2: improved the commit message with a better description of the
>           issue and the GCC bug number. No code change.

I think the comment, not just the commit message should explain the issue 
(i.e., that only libnldbl nonlib testsuite should logically be using 
-fmath-errno, but everything apart from libm is currently using 
-fmath-errno because of that GCC bug).

(I would say that the comment should give the GCC version in which the bug 
is fixed to make it obvious when we can change the code back, but that 
doesn't work when the GCC bug isn't yet fixed.)

Could you add a testcase to the testsuite (that appropriately interposes 
malloc to demonstrate the bug as in the one attached to the bug, thus 
failing before the Makeconfig fix and passing after it)?

-- 
Joseph S. Myers
joseph@codesourcery.com