Silence unused private member warning

Removed mConfig from Context and related functions.

Change-Id: I91eba6a4dbbd8ff48f212a246b1894009d513436
Reviewed-on: https://swiftshader-review.googlesource.com/5531
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
diff --git a/src/OpenGL/libGLESv2/main.cpp b/src/OpenGL/libGLESv2/main.cpp
index 001aa7a..12ed31d 100644
--- a/src/OpenGL/libGLESv2/main.cpp
+++ b/src/OpenGL/libGLESv2/main.cpp
@@ -1327,7 +1327,7 @@
 }
 }
 
-egl::Context *es2CreateContext(egl::Display *display, const egl::Config *config, const egl::Context *shareContext, int clientVersion);
+egl::Context *es2CreateContext(egl::Display *display, const egl::Context *shareContext, int clientVersion);
 extern "C" __eglMustCastToProperFunctionPointerType es2GetProcAddress(const char *procname);
 egl::Image *createBackBuffer(int width, int height, const egl::Config *config);
 egl::Image *createDepthStencil(unsigned int width, unsigned int height, sw::Format format, int multiSampleDepth, bool discard);