Fix Alpine Linux builds

Reported by Maxime Bouton.

* spot/misc/tmpfile.cc: Include stdlib.h, not cstdlib, so
that our replacement secure_getenv() is found.
* THANKS: Add Maxime.
12 jobs for next in 154 minutes and 35 seconds (queued for 1 second)
Status Name Job ID Coverage
  Build
passed arch-clang #21949

00:47:12

passed arch-gcc-glibcxxdebug #21950

00:40:01

passed debian-gcc-snapshot #21948

01:04:18

passed debian-stable-gcc #21946

00:38:41

passed debian-unstable-gcc-coverage #21947

00:37:51

88.8%
passed debpkg-stable #21953

02:03:39

passed debpkg-unstable #21954

02:09:17

passed mingw-shared #21951

00:07:32

passed mingw-static #21952

00:16:56

failed rpm-pkg #21955

00:37:58

 
  Publish
skipped publish-rpm #21956
dput
skipped publish-unstable #21957
dput
 
Name Stage Failure
failed
rpm-pkg Build


RPM build errors:
File not found: /root/rpmbuild/BUILDROOT/spot-2.6.3.dev-69.fc29.x86_64/usr/lib64/python3.7/site-packages/__pycache__/buddy.cpython-36.opt-1.pyc
File not found: /root/rpmbuild/BUILDROOT/spot-2.6.3.dev-69.fc29.x86_64/usr/lib64/python3.7/site-packages/__pycache__/buddy.cpython-36.pyc
Uploading artifacts...
WARNING: ./*.rpm: no matching files
ERROR: No files to upload
ERROR: Job failed: exit code 1