Reject copying from GL_RGB10_A2 to unsized formats.

glCopyTexImage2D() with an framebuffer format of GL_RGB10_A2 and
internalformat of GL_LUMINANCE_ALPHA was hitting the UNIMPLEMENTED()
assert.

The spec states that:
If an effective internal format exists that has
   * the same component sizes as,
   * component sizes greater than or equal to, or
   * component sizes smaller than or equal to
 those of the source buffer's effective internal format (for all
 matching components in <internalformat>), that format is chosen for
 the new image array and this is the effective internal format of the
 new texel array.

There is no unorm luminance+alpha format that has all components either
greater or smaller, so this operation is invalid.

Also see https://www.khronos.org/members/login/bugzilla/show_bug.cgi?id=9807#c56

Bug chromium:853424

Change-Id: Ia79a50bf7411a3f2aa87cf7f9bdbcbf971bdd7ce
Reviewed-on: https://swiftshader-review.googlesource.com/19768
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>

src/OpenGL/libGLESv2/libGLESv2.cpp

diff --git a/src/OpenGL/libGLESv2/libGLESv2.cpp b/src/OpenGL/libGLESv2/libGLESv2.cpp
index 7ae8126..b7ae2c5 100644
--- a/src/OpenGL/libGLESv2/libGLESv2.cpp
+++ b/src/OpenGL/libGLESv2/libGLESv2.cpp
@@ -930,6 +930,13 @@
 		// Determine the sized internal format.
 		if(gl::IsUnsizedInternalFormat(internalformat))
 		{
+			if(colorbufferFormat == GL_RGB10_A2)
+			{
+				// Not supported with unsized internalformat.
+				// https://www.khronos.org/members/login/bugzilla/show_bug.cgi?id=9807#c56
+				return error(GL_INVALID_OPERATION);
+			}
+
 			if(gl::GetBaseInternalFormat(colorbufferFormat) == internalformat)
 			{
 				internalformat = colorbufferFormat;
@@ -959,6 +966,7 @@
 			}
 			else
 			{
+				printf("internalformat = %x, colorbufferFormat = %X\n", internalformat, colorbufferFormat);
 				UNIMPLEMENTED();
 
 				return error(GL_INVALID_OPERATION);