BUG: KWSys symbols should not be exported with WINDOWS_EXPORT_ALL_SYMBOLS
BUG: KWSys symbols should not be exported with WINDOWS_EXPORT_ALL_SYMBOLS

Not disabling this option for KWSys leads to warning messages when
compiling ITK with Visual Studio 17:

Example or warning message:

ProcessWin32.obj : warning LNK4197: export 'itksysProcess_New' specified\
multiple times; using first specification [C:\Jenkins\workspace\ITKWinVS17\
ITK-bin\Modules\ThirdParty\KWSys\src\KWSys\itksys.vcxproj]

Change-Id: Iafadc2c726e76c52aeb3f7def91e358451c23c89

vfonov/ITK,PlutoniumHeart/ITK,BRAINSia/ITK,LucasGandel/ITK,stnava/ITK,Kitware/ITK,InsightSoftwareConsortium/ITK,fbudin69500/ITK,malaterre/ITK,thewtex/ITK,richardbeare/ITK,PlutoniumHeart/ITK,malaterre/ITK,vfonov/ITK,malaterre/ITK,thewtex/ITK,Kitware/ITK,stnava/ITK,thewtex/ITK,stnava/ITK,BRAINSia/ITK,malaterre/ITK,fbudin69500/ITK,LucasGandel/ITK,malaterre/ITK,stnava/ITK,LucasGandel/ITK,vfonov/ITK,vfonov/ITK,fbudin69500/ITK,hjmjohnson/ITK,blowekamp/ITK,Kitware/ITK,hjmjohnson/ITK,blowekamp/ITK,BRAINSia/ITK,PlutoniumHeart/ITK,richardbeare/ITK,spinicist/ITK,Kitware/ITK,thewtex/ITK,blowekamp/ITK,InsightSoftwareConsortium/ITK,InsightSoftwareConsortium/ITK,BRAINSia/ITK,InsightSoftwareConsortium/ITK,stnava/ITK,InsightSoftwareConsortium/ITK,BRAINSia/ITK,hjmjohnson/ITK,spinicist/ITK,spinicist/ITK,malaterre/ITK,spinicist/ITK,LucasGandel/ITK,vfonov/ITK,hjmjohnson/ITK,LucasGandel/ITK,hjmjohnson/ITK,spinicist/ITK,PlutoniumHeart/ITK,InsightSoftwareConsortium/ITK,hjmjohnson/ITK,PlutoniumHeart/ITK,PlutoniumHeart/ITK,thewtex/ITK,Kitware/ITK,spinicist/ITK,fbudin69500/ITK,richardbeare/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,Kitware/ITK,BRAINSia/ITK,blowekamp/ITK,vfonov/ITK,vfonov/ITK,fbudin69500/ITK,PlutoniumHeart/ITK,malaterre/ITK,spinicist/ITK,stnava/ITK,thewtex/ITK,Kitware/ITK,blowekamp/ITK,stnava/ITK,LucasGandel/ITK,richardbeare/ITK,blowekamp/ITK,richardbeare/ITK,hjmjohnson/ITK,stnava/ITK,blowekamp/ITK,PlutoniumHeart/ITK,richardbeare/ITK,BRAINSia/ITK,LucasGandel/ITK,blowekamp/ITK,LucasGandel/ITK,malaterre/ITK,thewtex/ITK,spinicist/ITK,spinicist/ITK,vfonov/ITK,fbudin69500/ITK,stnava/ITK,fbudin69500/ITK,fbudin69500/ITK,richardbeare/ITK,vfonov/ITK