Remove stray printfs.

SwiftShader shouldn't print anything to stdout in Release builds.

Also refactor UNIMPLEMENTED macro to be able to take a formatted string
with arguments.

Bug b/73656151

Change-Id: Ibadbfba3371324ba1bd608bd51bdac5e5923a20e
Reviewed-on: https://swiftshader-review.googlesource.com/21108
Reviewed-by: Merck Hung <merckhung@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>

src/OpenGL/libGLESv2/libGLESv2.cpp

diff --git a/src/OpenGL/libGLESv2/libGLESv2.cpp b/src/OpenGL/libGLESv2/libGLESv2.cpp
index 541b116..d8a4a8f 100644
--- a/src/OpenGL/libGLESv2/libGLESv2.cpp
+++ b/src/OpenGL/libGLESv2/libGLESv2.cpp
@@ -962,8 +962,7 @@
 			}
 			else
 			{
-				printf("internalformat = %x, colorbufferFormat = %X\n", internalformat, colorbufferFormat);
-				UNIMPLEMENTED();
+				UNIMPLEMENTED("internalformat = %x, colorbufferFormat = %X", internalformat, colorbufferFormat);
 
 				return error(GL_INVALID_OPERATION);
 			}