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Apply the apr-enable-ipv6.patch. Note that the patch will apply but depending on exactly which revision you are working with you may need to skip the first part of the patch and an offset will probably be required.
git apply apr-enable-ipv6.patch
git apply win-ipv6.patch
Then build
c:\cmsc\setenv.bat /x86
nmake -f NMAKEmakefile BUILD_CPU=x86 APR_DECLARE_STATIC=1 c:\cmsc\setenv.bat /x64 nmake -f NMAKEmakefile BUILD_CPU=x64 APR_DECLARE_STATIC=1 cd ..\openssl
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