bug#42910: libfive fails to build

[bdju]

guix (GNU Guix) 2a20c22dcf7b6a01eca5d1142d2a34c39f2f948a

It has been failing for some days now.

build log here:
http://ix.io/2uv3

This part was pointed out to me:
(libfive/test/heightmap.cpp:261:5: error: ‘BENCHMARK’ was not declared
in this scope)