Fix openssl flags
To detect openssl configuration is used ax_check_openssl.m4 whith sets the following flags
- OPENSSL_INCLUDES to the include directives required
- OPENSSL_LIBS to the -l directives required
- OPENSSL_LDFLAGS to the -L or -R flags required These flags are not propagated correctly to the stun makefile. More specifically, OPENSSL_CFLAGS doest not exist in the .m4 instead the openssl includes path are stored in the OPENSSL_INCLUDES flag.
We also have to pass the OPENSSL_LDFLAGS which contains the library path which is used by linker.
Also FIY that might be useful to someone who is trying to link the statically compiled library of openssl, we had to use LIBS="-ldl" env variable to be able to pass the ax_check_openssl.m4 compile and linking check and detect correctly the provided openssl lib instead of the system installed one.
Thanks for your effort to maintain this awesome "nice" :) library!