bug#50058: 28.0.5; emacs build fails with undefined reference to malloc_info

[Eli Zaretskii]

> From: birdsite@airmail.cc
> Date: Sat, 14 Aug 2021 19:26:12 +0545
> 
> Recently while building emacs from source in void-linux using musl libc,
> the make program exits saying undefined reference to malloc_info.
> 
> Using git-bisect, i've found that the problem started with commit
> 621bb79b7044dcc277386eb7338c0eb1e08c29c7 `New debugging command
> 'malloc-info''
> This commit was introduced in 2020 Nov 10
> 
> The problem is present in the HEAD as of 2021 Aug 11 with commit
> 244acc5a057b0d6ff03754af14d71808b6f20233 `Replace some `string-match-p'
> calls in Tramp'
> 
> I beleive the problem exists because i'm using musl libc and not glibc.

Does musl define some preprocessor macro that we could use to
condition that function's compilation?