Adding functionality to stencils

Two minor features are required for the blitFramebuffer
implementation in OpenGL ES 3:
- lockStencil with x,y coordinates
- getting the stencil format (new getStencilFormat function)

Change-Id: I83ccccefe70dbbedd05b5d82bc75d30f689c4abe
Reviewed-on: https://swiftshader-review.googlesource.com/7490
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
diff --git a/src/OpenGL/common/Image.cpp b/src/OpenGL/common/Image.cpp
index b7362d8..c734ba2 100644
--- a/src/OpenGL/common/Image.cpp
+++ b/src/OpenGL/common/Image.cpp
@@ -1627,7 +1627,7 @@
 	{
 		LoadImageData<D24>(xoffset, yoffset, zoffset, width, height, depth, inputPitch, inputHeight, getPitch(), getHeight(), input, buffer);
 
-		unsigned char *stencil = reinterpret_cast<unsigned char*>(lockStencil(0, sw::PUBLIC));
+		unsigned char *stencil = reinterpret_cast<unsigned char*>(lockStencil(0, 0, 0, sw::PUBLIC));
 
 		if(stencil)
 		{
@@ -1641,7 +1641,7 @@
 	{
 		LoadImageData<D32F>(xoffset, yoffset, zoffset, width, height, depth, inputPitch, inputHeight, getPitch(), getHeight(), input, buffer);
 
-		unsigned char *stencil = reinterpret_cast<unsigned char*>(lockStencil(0, sw::PUBLIC));
+		unsigned char *stencil = reinterpret_cast<unsigned char*>(lockStencil(0, 0, 0, sw::PUBLIC));
 
 		if(stencil)
 		{