Add support to Gamma Correction

[slime73]

Original report by Gustavo Guimaraes (Bitbucket: Ghust1995, ).

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Gamma correction does not work even on phones that was supposed to support it.

[slime73]

Original comment by Alex Szpakowski (Bitbucket: slime73, GitHub: slime73).

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love currently relies on the window manager / graphics driver exposing sRGB back buffer formats, for gamma correction to work. macOS, Linux, Windows, and iOS all support this but most or all Android devices don't. For love 0.11 I'm looking into some workarounds (e.g. #1102).

[MikuAuahDark]

Blocked by love2d/love#1106

[slime73]

Do we know if t.gammacorrect works as expected on Android devices which have the EGL_KHR_gl_colorspace extension?

I still want to do the virtual backbuffer thing on devices that don't support that extension since it's not super widely available, but it'd be good to know if things already work when it's available.

[MikuAuahDark]

Gamma correct rendering in Android is supported as of love2d/love@65667c0 (which needs EGL_KHR_gl_colorspace).