Fixed Windows warnings

- Removed unused variables
- Removed unreachable code
- Fixed size_t <-> int conversions
- Fixed uninitialized variables

Change-Id: Ifc3912e92b8f0710094e939bd0da4757148b559a
Reviewed-on: https://swiftshader-review.googlesource.com/5681
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
diff --git a/src/Shader/VertexShader.cpp b/src/Shader/VertexShader.cpp
index 06dd1b2..733c113 100644
--- a/src/Shader/VertexShader.cpp
+++ b/src/Shader/VertexShader.cpp
@@ -30,7 +30,7 @@
 
 		for(int i = 0; i < MAX_VERTEX_INPUTS; i++)
 		{
-			input[i] = Semantic(-1, -1);
+			input[i] = Semantic();
 		}
 
 		if(vs)   // Make a copy
@@ -62,7 +62,7 @@
 
 		for(int i = 0; i < MAX_VERTEX_INPUTS; i++)
 		{
-			input[i] = Semantic(-1, -1);
+			input[i] = Semantic();
 		}
 
 		optimize();