glGetString fix

glGetString wasn't returning es3 specific extensions.

Change-Id: Ief89eb448b3e821bfb7919ece97c03976569060c
Reviewed-on: https://swiftshader-review.googlesource.com/10954
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
diff --git a/src/OpenGL/libGLESv2/Context.cpp b/src/OpenGL/libGLESv2/Context.cpp
index ed1c366..aa68523 100644
--- a/src/OpenGL/libGLESv2/Context.cpp
+++ b/src/OpenGL/libGLESv2/Context.cpp
@@ -4370,6 +4370,14 @@
 			{
 				extensionsCat += std::string(extension) + " ";
 			}
+
+			if(clientVersion >= 3)
+			{
+				for(const char *extension : es3extensions)
+				{
+					extensionsCat += std::string(extension) + " ";
+				}
+			}
 		}
 
 		return (const GLubyte*)extensionsCat.c_str();