gource: add missing libX11

Grimmauld e2970e59 5d2326a3

+2
+2
pkgs/by-name/go/gource/package.nix
··· 13 glew, 14 libGLU, 15 libGL, 16 boost, 17 glm, 18 tinyxml, ··· 43 SDL2_image 44 libGLU 45 libGL 46 boost 47 glm 48 freetype
··· 13 glew, 14 libGLU, 15 libGL, 16 + libX11, 17 boost, 18 glm, 19 tinyxml, ··· 44 SDL2_image 45 libGLU 46 libGL 47 + libX11 48 boost 49 glm 50 freetype