glsl/standalone: set MaxVertexStreams

ARB_transform_feedback3 sets a minimum of 1, ARB_gpu_shader5 a minimum
of 4. It shouldn't matter too much, so choosing the later.
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/compiler/glsl/standalone.cpp

@@ -230,6 +230,7 @@ initialize_context(struct gl_context *ctx, gl_api api)
       ctx->Const.MaxTextureCoordUnits = 8;
       ctx->Const.MaxTextureUnits = 2;
       ctx->Const.MaxUniformBufferBindings = 84;
+      ctx->Const.MaxVertexStreams = 4;
 
       ctx->Const.Program[MESA_SHADER_VERTEX].MaxAttribs = 16;
       ctx->Const.Program[MESA_SHADER_VERTEX].MaxTextureImageUnits = 16;
@@ -264,6 +265,7 @@ initialize_context(struct gl_context *ctx, gl_api api)
       ctx->Const.MaxTextureCoordUnits = 8;
       ctx->Const.MaxTextureUnits = 2;
       ctx->Const.MaxUniformBufferBindings = 84;
+      ctx->Const.MaxVertexStreams = 4;
 
       ctx->Const.Program[MESA_SHADER_VERTEX].MaxAttribs = 16;
       ctx->Const.Program[MESA_SHADER_VERTEX].MaxTextureImageUnits = 16;
@@ -306,6 +308,7 @@ initialize_context(struct gl_context *ctx, gl_api api)
       ctx->Const.MaxTextureCoordUnits = 0;
       ctx->Const.MaxTextureUnits = 0;
       ctx->Const.MaxUniformBufferBindings = 84;
+      ctx->Const.MaxVertexStreams = 4;
 
       ctx->Const.Program[MESA_SHADER_VERTEX].MaxAttribs = 16;
       ctx->Const.Program[MESA_SHADER_VERTEX].MaxTextureImageUnits = 16;