Major Description
The configure check for tls1.h fails, because at least on openssl 1.0.2 tls1.h depends on a macro from openssl/safestack.h.
I've created pull request #180 on github to fix the detection by including openssl/ssl.h in the configure check, which in turn includes safestack.h. Given that ssl.h is already required that solution should be fully backwards compatible to older versions that might not require safestack.h.
This problem affects at least master and 5.2.0.