Fix bug when gc-cons-percentage is bumped to 0.8

Problem reported by Michael Heerdegen (Bug#37321).
* src/alloc.c (gc_threshold): New static var.
(bump_consing_until_gc): Change args from DIFF to THRESHOLD and
PERCENTAGE.  All uses changed.  When accounting for a changed
gc-cons-percentage, do not assume that total_bytes_of_live_objects
returns the same value now that it did the last time we were
called.
1 job for master in 62 minutes and 44 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #3229
test-all

01:02:44

 
Name Stage Failure
failed
test-all Test
Makefile:319: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
make[1]: *** [check-expensive] Error 2
Makefile:294: recipe for target 'check-expensive' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:959: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1