egl.api: Handle null contexts.
egl.api: Handle null contexts.

Fixes crash on many apps. Opps.

google/gapid,dsrbecky/gapid,google/agi,google/agi,baldwinn860/gapid,pmuetschard/gapid,google/gapid,google/gapid,pmuetschard/gapid,pmuetschard/gapid,google/gapid,baldwinn860/gapid,pmuetschard/gapid,baldwinn860/gapid,google/agi,dsrbecky/gapid,baldwinn860/gapid,google/agi,baldwinn860/gapid,dsrbecky/gapid,google/agi,baldwinn860/gapid,dsrbecky/gapid,dsrbecky/gapid,Qining/gapid,google/gapid,baldwinn860/gapid,Qining/gapid,google/agi,dsrbecky/gapid,google/agi,Qining/gapid,google/gapid,pmuetschard/gapid,google/gapid,pmuetschard/gapid,pmuetschard/gapid,Qining/gapid,dsrbecky/gapid,baldwinn860/gapid,google/agi,Qining/gapid,Qining/gapid,Qining/gapid,Qining/gapid,dsrbecky/gapid,google/gapid,pmuetschard/gapid