bug#38250: PHP 7.3.11 fails its test suite

[Maxim Cournoyer]

Whenever I tried building PHP as of Guix commit
2484e0b3e481e2b1fcb6761d0dbf80da98089de4, the following tests fail:

=====================================================================
FAILED TEST SUMMARY
---------------------------------------------------------------------
Test disk_free_space and its alias diskfreespace() functions : basic 
functionality [ext/standard/tests/fi
Test lstat() and stat() functions: usage variations - creating file/subdir 
[ext/standard/tests/file/lstat
Test lstat() and stat() functions: usage variations - deleting file/subdir 
[ext/standard/tests/file/lstat
=====================================================================

The CI seems to be OK with it (I get a substitute).  I wonder if it has
to do with my specific machine (X200).  It's equipped with 8 GB of RAM
and 9 GB of swap.

Maxim