cmake: Add -DWAFFLE_HAS_TLS if compiler supports the tls_model attribute
cmake: Add -DWAFFLE_HAS_TLS if compiler supports the tls_model attribute

Specifically, the compiler must support this code snippet contained in the
CheckThreadLocalStorage module:

    static __thread int x __attribute__((tls_model("initial-exec")));

Signed-off-by: Chad Versace <a557f7f75bf28dc19ac99107f5cc7cd6b3fbdb1a@linux.intel.com>

chadversary/waffle,yinquan529/waffle-gl-waffle,maurossi/waffle,janesma/waffle,dcbaker/waffle,yinquan529/waffle-gl-waffle,waffle-gl/waffle,maurossi/waffle,fjhenigman/waffle,chadversary/waffle,evelikov/waffle,waffle-gl/waffle,evelikov/waffle,fjhenigman/waffle,waffle-gl/waffle,evelikov/waffle,janesma/waffle,dcbaker/waffle,dcbaker/waffle,fjhenigman/waffle,maurossi/waffle,waffle-gl/waffle,chadversary/waffle,janesma/waffle,yinquan529/waffle-gl-waffle