Fixed signed/unsigned types comparison

BUG=18368388

Change-Id: I3f2927fd68e75a8fb5abde1b25e81416862076fc
Reviewed-on: https://swiftshader-review.googlesource.com/1474
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
diff --git a/src/Shader/Shader.cpp b/src/Shader/Shader.cpp
index fc98eb5..aa5b30d 100644
--- a/src/Shader/Shader.cpp
+++ b/src/Shader/Shader.cpp
@@ -1457,7 +1457,7 @@
 				instruction[0]->opcode = OPCODE_NULL;
 				instruction[1]->opcode = OPCODE_NULL;
 
-				for(int i = 2; i < instruction.size(); i++)
+				for(size_t i = 2; i < instruction.size(); i++)
 				{
 					if(instruction[i]->opcode == OPCODE_LABEL || instruction[i]->opcode == OPCODE_RET)
 					{
@@ -1470,8 +1470,8 @@
 
 	void Shader::removeNull()
 	{
-		int size = 0;
-		for(int i = 0; i < instruction.size(); i++)
+		size_t size = 0;
+		for(size_t i = 0; i < instruction.size(); i++)
 		{
 			if(instruction[i]->opcode != OPCODE_NULL)
 			{