tests: sniff for /usr/local/bin/gmake and use it in test-fuzz-targets.t
This isn't as robust as it probably should be, but for now it'll get
the job done on the buildbots.
Differential Revision: https://phab.mercurial-scm.org/D5269
pager.pager=p0 # $TESTTMP/sysrc:4
ui.editor=e1 # $TESTTMP/userrc:2
pager.pager=p2 # $PAGER
ui.editor=e1 # $TESTTMP/userrc:2