Doxygen fixes.

src/AbstractFramebuffer.cpp

@@ -25,11 +25,11 @@
 
 namespace Magnum {
 
+#ifndef DOXYGEN_GENERATING_OUTPUT
 AbstractFramebuffer::DrawBuffersImplementation AbstractFramebuffer::drawBuffersImplementation = &AbstractFramebuffer::drawBuffersImplementationDefault;
 AbstractFramebuffer::DrawBufferImplementation AbstractFramebuffer::drawBufferImplementation = &AbstractFramebuffer::drawBufferImplementationDefault;
 AbstractFramebuffer::ReadBufferImplementation AbstractFramebuffer::readBufferImplementation = &AbstractFramebuffer::readBufferImplementationDefault;
 
-#ifndef DOXYGEN_GENERATING_OUTPUT
 AbstractFramebuffer::Target AbstractFramebuffer::readTarget = AbstractFramebuffer::Target::ReadDraw;
 AbstractFramebuffer::Target AbstractFramebuffer::drawTarget = AbstractFramebuffer::Target::ReadDraw;
 #endif