ENH: Teach KWSys Process basic VMS support
ENH: Teach KWSys Process basic VMS support

This achieves basic process execution on OpenVMS.  We use work-arounds
for different fork()/exec() behavior and a lack of select().

VMS emulates fork/exec using setjmp/longjmp to evaluate the child and
parent return cases from fork.  Therefore both must be invoked from the
same function.

Since select() works only for sockets we use the BeOS-style polling
implementation.  However, non-blocking reads on empty pipes cannot be
distinguished easily from the last read on a closed pipe.  Therefore we
identify end of data by an empty read after the child terminates.

thewtex/ITK,Kitware/ITK,LucasGandel/ITK,PlutoniumHeart/ITK,fedral/ITK,itkvideo/ITK,BRAINSia/ITK,daviddoria/itkHoughTransform,InsightSoftwareConsortium/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,malaterre/ITK,hjmjohnson/ITK,PlutoniumHeart/ITK,jmerkow/ITK,heimdali/ITK,CapeDrew/DITK,atsnyder/ITK,paulnovo/ITK,CapeDrew/DCMTK-ITK,hinerm/ITK,hinerm/ITK,heimdali/ITK,thewtex/ITK,rhgong/itk-with-dom,jcfr/ITK,cpatrick/ITK-RemoteIO,PlutoniumHeart/ITK,CapeDrew/DITK,jcfr/ITK,atsnyder/ITK,hendradarwin/ITK,daviddoria/itkHoughTransform,CapeDrew/DCMTK-ITK,thewtex/ITK,atsnyder/ITK,spinicist/ITK,hinerm/ITK,CapeDrew/DCMTK-ITK,fbudin69500/ITK,LucHermitte/ITK,fuentesdt/InsightToolkit-dev,LucHermitte/ITK,msmolens/ITK,jcfr/ITK,biotrump/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,spinicist/ITK,vfonov/ITK,biotrump/ITK,cpatrick/ITK-RemoteIO,rhgong/itk-with-dom,jcfr/ITK,blowekamp/ITK,CapeDrew/DCMTK-ITK,fuentesdt/InsightToolkit-dev,fbudin69500/ITK,wkjeong/ITK,jmerkow/ITK,richardbeare/ITK,stnava/ITK,wkjeong/ITK,LucasGandel/ITK,msmolens/ITK,LucasGandel/ITK,Kitware/ITK,fbudin69500/ITK,msmolens/ITK,msmolens/ITK,jmerkow/ITK,vfonov/ITK,CapeDrew/DITK,Kitware/ITK,ajjl/ITK,hendradarwin/ITK,hjmjohnson/ITK,GEHC-Surgery/ITK,ajjl/ITK,vfonov/ITK,zachary-williamson/ITK,blowekamp/ITK,BlueBrain/ITK,LucHermitte/ITK,heimdali/ITK,daviddoria/itkHoughTransform,itkvideo/ITK,fuentesdt/InsightToolkit-dev,CapeDrew/DCMTK-ITK,ajjl/ITK,rhgong/itk-with-dom,heimdali/ITK,InsightSoftwareConsortium/ITK,wkjeong/ITK,Kitware/ITK,zachary-williamson/ITK,richardbeare/ITK,malaterre/ITK,BlueBrain/ITK,LucHermitte/ITK,blowekamp/ITK,thewtex/ITK,richardbeare/ITK,paulnovo/ITK,biotrump/ITK,paulnovo/ITK,cpatrick/ITK-RemoteIO,ajjl/ITK,hinerm/ITK,GEHC-Surgery/ITK,msmolens/ITK,malaterre/ITK,BRAINSia/ITK,wkjeong/ITK,atsnyder/ITK,atsnyder/ITK,msmolens/ITK,hendradarwin/ITK,InsightSoftwareConsortium/ITK,jcfr/ITK,BlueBrain/ITK,daviddoria/itkHoughTransform,hinerm/ITK,paulnovo/ITK,eile/ITK,atsnyder/ITK,spinicist/ITK,ajjl/ITK,rhgong/itk-with-dom,biotrump/ITK,BlueBrain/ITK,zachary-williamson/ITK,fuentesdt/InsightToolkit-dev,thewtex/ITK,wkjeong/ITK,fedral/ITK,BlueBrain/ITK,paulnovo/ITK,CapeDrew/DITK,stnava/ITK,Kitware/ITK,zachary-williamson/ITK,fuentesdt/InsightToolkit-dev,LucasGandel/ITK,cpatrick/ITK-RemoteIO,spinicist/ITK,PlutoniumHeart/ITK,GEHC-Surgery/ITK,ajjl/ITK,CapeDrew/DCMTK-ITK,msmolens/ITK,CapeDrew/DITK,atsnyder/ITK,fuentesdt/InsightToolkit-dev,ajjl/ITK,heimdali/ITK,LucasGandel/ITK,Kitware/ITK,spinicist/ITK,LucHermitte/ITK,stnava/ITK,eile/ITK,CapeDrew/DITK,wkjeong/ITK,heimdali/ITK,eile/ITK,heimdali/ITK,BRAINSia/ITK,eile/ITK,richardbeare/ITK,fuentesdt/InsightToolkit-dev,hjmjohnson/ITK,GEHC-Surgery/ITK,cpatrick/ITK-RemoteIO,rhgong/itk-with-dom,LucasGandel/ITK,CapeDrew/DITK,stnava/ITK,malaterre/ITK,atsnyder/ITK,hinerm/ITK,cpatrick/ITK-RemoteIO,daviddoria/itkHoughTransform,richardbeare/ITK,richardbeare/ITK,fedral/ITK,hinerm/ITK,blowekamp/ITK,daviddoria/itkHoughTransform,stnava/ITK,fuentesdt/InsightToolkit-dev,hendradarwin/ITK,BRAINSia/ITK,malaterre/ITK,PlutoniumHeart/ITK,itkvideo/ITK,wkjeong/ITK,hendradarwin/ITK,fbudin69500/ITK,zachary-williamson/ITK,stnava/ITK,stnava/ITK,InsightSoftwareConsortium/ITK,CapeDrew/DCMTK-ITK,hjmjohnson/ITK,eile/ITK,spinicist/ITK,cpatrick/ITK-RemoteIO,fedral/ITK,BRAINSia/ITK,spinicist/ITK,PlutoniumHeart/ITK,spinicist/ITK,eile/ITK,msmolens/ITK,CapeDrew/DITK,itkvideo/ITK,itkvideo/ITK,eile/ITK,paulnovo/ITK,biotrump/ITK,GEHC-Surgery/ITK,rhgong/itk-with-dom,itkvideo/ITK,blowekamp/ITK,blowekamp/ITK,hendradarwin/ITK,InsightSoftwareConsortium/ITK,jcfr/ITK,wkjeong/ITK,fedral/ITK,BlueBrain/ITK,hinerm/ITK,vfonov/ITK,hendradarwin/ITK,LucHermitte/ITK,hjmjohnson/ITK,CapeDrew/DCMTK-ITK,cpatrick/ITK-RemoteIO,thewtex/ITK,biotrump/ITK,eile/ITK,CapeDrew/DITK,jmerkow/ITK,LucasGandel/ITK,Kitware/ITK,hjmjohnson/ITK,zachary-williamson/ITK,LucasGandel/ITK,malaterre/ITK,malaterre/ITK,vfonov/ITK,fbudin69500/ITK,GEHC-Surgery/ITK,daviddoria/itkHoughTransform,thewtex/ITK,vfonov/ITK,fedral/ITK,stnava/ITK,rhgong/itk-with-dom,vfonov/ITK,paulnovo/ITK,zachary-williamson/ITK,paulnovo/ITK,eile/ITK,PlutoniumHeart/ITK,LucHermitte/ITK,fbudin69500/ITK,GEHC-Surgery/ITK,BRAINSia/ITK,fbudin69500/ITK,hjmjohnson/ITK,blowekamp/ITK,zachary-williamson/ITK,fedral/ITK,blowekamp/ITK,daviddoria/itkHoughTransform,GEHC-Surgery/ITK,vfonov/ITK,jmerkow/ITK,heimdali/ITK,jmerkow/ITK,biotrump/ITK,jmerkow/ITK,zachary-williamson/ITK,fbudin69500/ITK,BRAINSia/ITK,malaterre/ITK,BlueBrain/ITK,hinerm/ITK,jcfr/ITK,hendradarwin/ITK,atsnyder/ITK,daviddoria/itkHoughTransform,itkvideo/ITK,ajjl/ITK,jmerkow/ITK,spinicist/ITK,biotrump/ITK,itkvideo/ITK,stnava/ITK,LucHermitte/ITK,PlutoniumHeart/ITK,CapeDrew/DCMTK-ITK,BlueBrain/ITK,jcfr/ITK,fuentesdt/InsightToolkit-dev,itkvideo/ITK,richardbeare/ITK,rhgong/itk-with-dom,fedral/ITK