Build with newer openssl headers on build machines (Mac)

It seems the mac packages on the build machines are built with headers from a rather out-of-date openssl. Regardless of the openssl version at runtime, TLSv1.1, TLSV1.2 are not supported.

A quick check whether we compiled with OpenSSL 1.0.1 and newer is check e.g. for TLSv1_2 symbols:

nm QtNetwork.framework/Versions/Current/QtNetwork | grep TLSv1_2

should show some symbols.

To compile Qt with a custom openssl you need to set two environment variables, e.g.

export CPATH=/usr/local/openssl/include
export LIBRARY_PATH=/usr/local/openssl/lib
./configure [...]

(passing -I, -L to configure does taint the resulting SDK with the build paths)