Add freeglut and xorgproto as makedepends

Xorgproto was mentioned in a comment, and the script skia uses to
download dependencies mentions freeglut.

.SRCINFO

@@ -9,6 +9,8 @@ pkgbase = aseprite
 	makedepends = ninja
 	makedepends = git
 	makedepends = python2
+	makedepends = freeglut
+	makedepends = xorgproto
 	depends = cmark
 	depends = curl
 	depends = giflib

PKGBUILD

@@ -15,7 +15,7 @@ url="http://www.aseprite.org/"
 license=('custom')
 depends=('cmark' 'curl' 'giflib' 'zlib' 'libpng' 'tinyxml' 'freetype2'
          'harfbuzz' 'nettle' 'fontconfig' 'libxcursor' 'hicolor-icon-theme')
-makedepends=('cmake' 'ninja' 'git' 'python2')
+makedepends=('cmake' 'ninja' 'git' 'python2' 'freeglut' 'xorgproto')
 conflicts=("aseprite-git" "aseprite-gpl" "skia-git")
 source=("https://github.com/${pkgname}/${pkgname}/releases/download/v${pkgver}/${pkgname^}-\
 v${pkgver}-Source.zip"