* gc.c: relax GC condition due to malloc_limit.
* gc.c (GC_MALLOC_LIMIT_MAX): change default value
  (256MB -> 512MB) and permit zero to ignore max value.
* gc.c (vm_malloc_increase, vm_xrealloc): do not cause GC on realloc.
* gc.c (gc_before_sweep): change debug messages.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43119 b2dd03c8-39d4-4d8f-98ff-823fe69b080e