Raspbian stretch egl library fix

[rasmuspeders1]

Proposed fix for replacing the names of libraries EGL and GLESv2 to brcmEGL and brcmGLESv2 which seems like the correct way to get kivy to use the closed source broadcom ELG GLESv2 libs on raspian stretch.

Only replaces the names if platform is rpi and linux dist is debian 9.1 or newer.

Proposed fix inspired from this issue report: #5341

[dbgasaway]

Is release 9.1 the correct release to compare to? These libraries are actually available under the new names in 8.0, at least on my pi, and it's possible someone with 9.0 could have these problems as well (if that's even possible to have as a version on a pi).

Also, the current code (in my understanding) checks if it's an rpi by checking for the existence of the file /opt/vc/include/bcm_host.h on line 129 at https://github.com/rasmuspeders1/kivy/blob/6043834d4532b67cab6e01783883467f0db96b99/setup.py#L129. Maybe the best solution for detecting the new library names, using a similar technique, would be to check for the libbrcmGLESv2 and libbrcmEGL files in /opt/vc/lib/? Especially considering that it's already manually adding the /opt/vc/lib/ include directory, and it avoids checking a high-level feature like a Debian release version.

[rasmuspeders1]

I agree @dbgasaway. The idea withe simply checking the distribution and version was to affect only this and newer distros.
I like your idea with checking if libbrcmEGL and libbrcmGLESv2 exists better. This could potentially solve the issue on different and older distros as well, provided they follow the same naming convention as Raspbian. And it should be at least as safe as my original proposed fix.

I will push a change with this different solution to the pull request.

[rasmuspeders1]

The pull request is updated. It has been tested successfully on a rpi with rasbian stretch.

[tito]

Looks good, thanks you!