This reverts commit dd815b62.

Reason for revert: Broke https://luci-milo.appspot.com/p/chromium/builders/luci.chromium.ci/win-rel/8006

Original change's description:
> Load correct libGLESv2 on Linux and Mac.
> 
> libEGL was implicitly loading libGLESv2 on startup. This is bad
> because on platforms like Linux and Mac we could sometimes use the
> incorrect rpath. This in turn meant we needed workarounds like using
> "_angle" extensions to our shared objects to get the correct loading
> behaviour.
> 
> Fix this by loading libGLESv2 dynamically in libEGL. We build the
> loader automatically from egl.xml. The loader itself is lazily
> initialized on every EGL entry point call. This is necessary because
> on Linux, etc, there is no equivalent to Windows' DLLMain.
> 
> We also use an EGL.h with different generation options so we have the
> proper function pointer types. A README is included for instructions
> on how to regenerate EGL.h.
> 
> The entry point generation script is refactored into a helper class
> that is used in the loader generator. Also adds the libGLESv2 versions
> of the EGL entry points in the DEF file on Windows. This allows them to
> be imported properly in 32-bit configurations.
> 
> Also fixes up some errors in ANGLE's entry point definitions. Also
> includes a clang-format disable rule for the Khronos headers.
> 
> This CL will help us to run ANGLE tests against native drivers.
> 
> Bug: angleproject:2871
> Change-Id: Id6ecf969308f17b1be4083538428c9c1a1836572
> Reviewed-on: https://chromium-review.googlesource.com/c/1370725
> Commit-Queue: Jamie Madill <jmadill@chromium.org>
> Reviewed-by: Geoff Lang <geofflang@chromium.org>

TBR=ynovikov@chromium.org,geofflang@chromium.org,jmadill@chromium.org

Change-Id: I921b3c45435ab4f05cbc2d1c1172b4185d6257b0
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: angleproject:2871
Reviewed-on: https://chromium-review.googlesource.com/c/1378887Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>