win32.h: define or declare finite always

* include/ruby/win32.h (finite): always define or declare.  some
  mingw (maybe w64 only?) lack the declaration.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43246 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
vm_trace.c: suppress warnings

* vm_trace.c (rb_postponed_job_flush): suppress clobbered variable
  warnings on some gcc.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43247 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
vm_trace.c: use macro

* vm_trace.c (rb_postponed_job_flush): use dedicated macro.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43248 b2dd03c8-39d4-4d8f-98ff-823fe69b080e