When built with mklove, WITH_SASL_SCRAM is set if WITH_SSL is set:

When built with cmake, WITH_SASL is set (by default) only if libsasl2 (cyrus-sasl) is found by pkg-config, or if a test program successfully links against -lsasl2:

WITH_SASL_SCRAM is then only enabled if WITH_SASL is set:

This means that when building with cmake, you need to either override -DWITH_SASL=ON or you'll never get SASL support that isn't SASL_CYRUS.

My suggestions:

1. The check for libsasl2 should have the try_compile() outside of the if(WITH_PKGCONFIG) guard:

   if(WITH_PKGCONFIG)
     pkg_check_modules(SASL libsasl2)
     if(SASL_FOUND)
       set(with_sasl_default ON)
     endif()
   else()
     try_compile(WITH_SASL_CYRUS_BOOL ...)
     if(WITH_SASL_CYRUS_BOOL)
       set(with_sasl_default ON)
       set(SASL_LIBRARIES "-lsasl2")
     endif()
   endif()

2. The check for if(WITH_SSL) should be hoisted outside of the if(WITH_SASL) guard, so that if OpenSSL is present, SASL_SCRAM and SASL_OATHBEARER can be used.