* [core]: fix window border alpha with invert effect profile

The bug appeared in preparation of the xcalib -i -a  effect simulation
inside oyranos-monitor.

oyranos-cms/oyranos#34
OpenICC/xcalib#4

compicc.c

@@ -406,8 +406,8 @@ static int getProfileShader(CompScreen *s, CompTexture *texture, int param, int
   /* colour transform through a texture lookup */
   addDataOpToFunctionData(data, "TEX output, output, texture[%d], 3D;", unit);
 
-  /* recover alpha */
-  addDataOpToFunctionData(data, "MOV output.a, temp.a;");
+  /* multiply alpha */
+  addDataOpToFunctionData(data, "MUL output, temp.a, output;");
 
   addColorOpToFunctionData (data, "output", "output");