BUG: don't quote argument to URL_HASH for FFTW
BUG: don't quote argument to URL_HASH for FFTW

The hash method was switched from URL_MD5 to URL_HASH in:

https://github.com/InsightSoftwareConsortium/ITK/commit/716fe079a6fad64f63f1166c7cb1565acef982ee#diff-3410c0d07b017317e4e05d74e9ad6941

Unfortunately, doing so with quoting breaks the the build due to a subtle difference in how URL_MD5 and URL_HASH are interpreted. See the following CMake MR for more information:

https://gitlab.kitware.com/cmake/cmake/merge_requests/2718

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