This is a reland of 5fcfcea4

Re-land uses static linking with angle_util. The root cause
of the CFI error wasn't solved. Static linking works around
the problem by not using any export rules.

Second re-land fixes missing imports for libEGL and libGLESv2
static varieties.

Original change's description:
> Add more test_utils functions.
>
> Includes methods for creating temporary files, deleting files, and
> reading files into a string. Also renames GetPathSeparator to mention
> it's only used for environment variables. Includes a new virtual type
> angle::Process that will be used to implement cross-platform async
> Process launching for tests. Also includes a way to specify a custom
> crash handler callback.
>
> Also adds a few unit tests for the new functionality. They are disabled
> on Android because the functions are not needed by the new test runner.
>
> Bug: angleproject:3162
> Change-Id: I3e2c2e9837608884c98379fa0f78c9ffbe158d73
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1821940
> Commit-Queue: Jamie Madill <jmadill@chromium.org>
> Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>

Bug: chromium:1015810
Bug: angleproject:3162
Change-Id: I2a18b819b0f91df610ad12ffedea2b38349fe7cf
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1879859
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>