Convert additional cflags comments into accessible pkg-config's vars.
Convert additional cflags comments into accessible pkg-config's vars.

The additional flags are usually trivial on *nix platforms but they are not so on Windows platform for MSVC.

kostik1337/Urho3D,victorholt/Urho3D,orefkov/Urho3D,rokups/Urho3D,c4augustus/Urho3D,PredatorMF/Urho3D,tommy3/Urho3D,codedash64/Urho3D,299299/Urho3D,299299/Urho3D,fire/Urho3D-1,carnalis/Urho3D,299299/Urho3D,carnalis/Urho3D,orefkov/Urho3D,SirNate0/Urho3D,PredatorMF/Urho3D,codemon66/Urho3D,tommy3/Urho3D,SirNate0/Urho3D,xiliu98/Urho3D,eugeneko/Urho3D,MonkeyFirst/Urho3D,SirNate0/Urho3D,weitjong/Urho3D,tommy3/Urho3D,codedash64/Urho3D,eugeneko/Urho3D,luveti/Urho3D,codemon66/Urho3D,rokups/Urho3D,SuperWangKai/Urho3D,iainmerrick/Urho3D,cosmy1/Urho3D,fire/Urho3D-1,MonkeyFirst/Urho3D,abdllhbyrktr/Urho3D,bacsmar/Urho3D,urho3d/Urho3D,cosmy1/Urho3D,kostik1337/Urho3D,cosmy1/Urho3D,abdllhbyrktr/Urho3D,c4augustus/Urho3D,MonkeyFirst/Urho3D,henu/Urho3D,c4augustus/Urho3D,orefkov/Urho3D,rokups/Urho3D,kostik1337/Urho3D,MeshGeometry/Urho3D,abdllhbyrktr/Urho3D,carnalis/Urho3D,tommy3/Urho3D,codemon66/Urho3D,xiliu98/Urho3D,henu/Urho3D,299299/Urho3D,MeshGeometry/Urho3D,rokups/Urho3D,urho3d/Urho3D,kostik1337/Urho3D,bacsmar/Urho3D,MeshGeometry/Urho3D,SirNate0/Urho3D,henu/Urho3D,c4augustus/Urho3D,helingping/Urho3D,helingping/Urho3D,luveti/Urho3D,xiliu98/Urho3D,victorholt/Urho3D,MeshGeometry/Urho3D,eugeneko/Urho3D,rokups/Urho3D,helingping/Urho3D,carnalis/Urho3D,SuperWangKai/Urho3D,cosmy1/Urho3D,kostik1337/Urho3D,henu/Urho3D,MonkeyFirst/Urho3D,c4augustus/Urho3D,SuperWangKai/Urho3D,orefkov/Urho3D,luveti/Urho3D,eugeneko/Urho3D,luveti/Urho3D,victorholt/Urho3D,codedash64/Urho3D,299299/Urho3D,weitjong/Urho3D,victorholt/Urho3D,bacsmar/Urho3D,tommy3/Urho3D,carnalis/Urho3D,codemon66/Urho3D,iainmerrick/Urho3D,urho3d/Urho3D,codedash64/Urho3D,PredatorMF/Urho3D,luveti/Urho3D,SirNate0/Urho3D,weitjong/Urho3D,fire/Urho3D-1,rokups/Urho3D,codemon66/Urho3D,PredatorMF/Urho3D,weitjong/Urho3D,299299/Urho3D,xiliu98/Urho3D,weitjong/Urho3D,SuperWangKai/Urho3D,cosmy1/Urho3D,xiliu98/Urho3D,abdllhbyrktr/Urho3D,henu/Urho3D,iainmerrick/Urho3D,MonkeyFirst/Urho3D,fire/Urho3D-1,abdllhbyrktr/Urho3D,helingping/Urho3D,victorholt/Urho3D,helingping/Urho3D,MeshGeometry/Urho3D,urho3d/Urho3D,iainmerrick/Urho3D,codedash64/Urho3D,SuperWangKai/Urho3D,fire/Urho3D-1,bacsmar/Urho3D,iainmerrick/Urho3D