Plasma and qt apps broken after upgrade in Testing

[devfra <devfra_pub@inventati.org>]

Hi list

I upgraded Testing this morning and now Plasma 5 and all the qt 
applications are broken.

Sddm does not work, it just shows me a black screen and the mouse 
cursor. I am also unable to start Plasma with another display manager 
(lightdm in my case).

I am now in an xfce session, all the qt applications do not work and 
give me always the same error:

    kcalc: symbol lookup error: /usr/lib/x86_64-linux-gnu/libGL.so.1: 
undefined symbol: _glapi_tls_Current
    transmission-qt: symbol lookup error: 
/usr/lib/x86_64-linux-gnu/libGL.so.1: undefined symbol: 
_glapi_tls_Current
    kwrite: symbol lookup error: /usr/lib/x86_64-linux-gnu/libGL.so.1: 
undefined symbol: _glapi_tls_Current
    ....

I tried to downgrade the liblgl1 and libglx0 packages to a previous 
version from debian snapshot but the problem remains.

This [0] is the list of the packages upgraded this morning. Thanks in 
advance for any help.

[0] https://paste.debian.net/hidden/938ee68a/