bug#25774: libmicrohttpd: fails to build (test-driver aborted)

[Ivan Vilata i Balaguer <ivan@selidor.net>]

libmicrohttpd-0.9.52 fails to build because of a failing test:

```
$ guix package -i libmicrohttpd
...
make[4]: Entering directory '/tmp/guix-build-libmicrohttpd-0.9.52.drv-0/libmicrohttpd-0.9.52/src/microhttpd'
PASS: test_str_compare
PASS: test_str_to_value
PASS: test_shutdown_select
PASS: test_shutdown_poll
PASS: test_daemon
PASS: test_upgrade
../../test-driver: line 107:  7381 Aborted                 "$@" > $log_file 2>&1
FAIL: test_upgrade_ssl
PASS: test_postprocessor
PASS: test_postprocessor_large
PASS: test_postprocessor_amp
============================================================================
Testsuite summary for GNU Libmicrohttpd 0.9.52
============================================================================
# TOTAL: 10
# PASS:  9
# SKIP:  0
# XFAIL: 0
# FAIL:  1
# XPASS: 0
# ERROR: 0
============================================================================
See src/microhttpd/test-suite.log
Please report to libmicrohttpd@gnu.org
============================================================================
make[4]: *** [Makefile:1289: test-suite.log] Error 1
make[4]: Leaving directory '/tmp/guix-build-libmicrohttpd-0.9.52.drv-0/libmicrohttpd-0.9.52/src/microhttpd'
make[3]: *** [Makefile:1397: check-TESTS] Error 2
make[3]: Leaving directory '/tmp/guix-build-libmicrohttpd-0.9.52.drv-0/libmicrohttpd-0.9.52/src/microhttpd'
make[2]: *** [Makefile:1531: check-am] Error 2
make[2]: Leaving directory '/tmp/guix-build-libmicrohttpd-0.9.52.drv-0/libmicrohttpd-0.9.52/src/microhttpd'
make[1]: *** [Makefile:429: check-recursive] Error 1
make[1]: Leaving directory '/tmp/guix-build-libmicrohttpd-0.9.52.drv-0/libmicrohttpd-0.9.52/src'
make: *** [Makefile:552: check-recursive] Error 1
phase `check' failed after 29.6 seconds
builder for `/gnu/store/42f3rhpv298bmi6ipd0la6nssx34hk6l-libmicrohttpd-0.9.52.drv' failed with exit code 1
guix package: error: build failed: build of `/gnu/store/42f3rhpv298bmi6ipd0la6nssx34hk6l-libmicrohttpd-0.9.52.drv' failed
```

This breaks transitively dependant packages as GNUnet.

Thank you!

-- 
Ivan Vilata i Balaguer -- https://elvil.net/