Add missing varying in and out qualifiers to the interpolation qualifier switch statement.

This was causing a benign assert in Debug mode with GLSL ES 1.00 shaders.

TRAC #23746

Signed-off-by: Shannon Woods
diff --git a/src/compiler/OutputHLSL.cpp b/src/compiler/OutputHLSL.cpp
index f0093ab..0a854c7 100644
--- a/src/compiler/OutputHLSL.cpp
+++ b/src/compiler/OutputHLSL.cpp
@@ -3637,6 +3637,8 @@
       case EvqSmoothOut:
       case EvqVertexOut:
       case EvqFragmentIn:
+      case EvqVaryingIn:
+      case EvqVaryingOut:
         return INTERPOLATION_SMOOTH;
 
       case EvqCentroidIn: