COMP: Correct ifndef value to allow user defined ITK_TEMPLATE_EXPORT
COMP: Correct ifndef value to allow user defined ITK_TEMPLATE_EXPORT

Allow the user to override ITK_TEMPLATE_EXPORT, by defining it before
include itkMacro.h.

Change-Id: I656454594daea7c3c2dac7cf85d0759b0404a995

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