Make the number of vertex outputs configurable.

Change-Id: I17ae53e5274232e9e3b482daac56d507788e822c
Reviewed-on: https://swiftshader-review.googlesource.com/5383
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>
diff --git a/src/Shader/VertexShader.cpp b/src/Shader/VertexShader.cpp
index cfbda0c..c488630 100644
--- a/src/Shader/VertexShader.cpp
+++ b/src/Shader/VertexShader.cpp
@@ -25,7 +25,7 @@
 	{
 		version = 0x0300;
 		positionRegister = Pos;
-		pointSizeRegister = -1;   // No vertex point size
+		pointSizeRegister = Unused;
 		instanceIdDeclared = false;
 
 		for(int i = 0; i < MAX_INPUT_ATTRIBUTES; i++)
@@ -57,7 +57,7 @@
 		parse(token);
 
 		positionRegister = Pos;
-		pointSizeRegister = -1;   // No vertex point size
+		pointSizeRegister = Unused;
 		instanceIdDeclared = false;
 
 		for(int i = 0; i < MAX_INPUT_ATTRIBUTES; i++)