OpenGL ES is not installed by default on linux distributions, which
can lead to a cryptic error. Add a comment after the #include
mentioning what packages contain OpenGL ES on Ubuntu, which is
helpfully printed in the error message. For example:
$ go build golang.org/x/mobile/example/basic
# golang.org/x/mobile/gl
In file included from ../../mobile/gl/work.go:21:0:
work.h:6:117: fatal error: GLES2/gl2.h: No such file or directory
#include <GLES2/gl2.h> // install on Ubuntu with: sudo apt-get install libegl1-mesa-dev libgles2-mesa-dev libx11-dev
Change-Id: Ia7ba583cee4dfdeed408f582b29da90de9a4fab3
Reviewed-on: https://go-review.googlesource.com/18058
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>