Minor INFINITY/NAN cleanup

* src/lread.c (INFINITY): Use a more-portable way to specify
this macro on non-C99 platforms that lack it.
(NAN): Remove; unused.
1 job for master in 22 minutes and 35 seconds (queued for 3 seconds)
Status Job ID Name Coverage
failed #479


Name Stage Failure
test Test
Makefile:309: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:279: recipe for target 'check' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
make[1]: *** [check] Error 2
Makefile:955: recipe for target 'check' failed
make: *** [check] Error 2
ERROR: Job failed: exit code 1