This reverts commit 7923e234.

Reason for revert: Fails compilation on rollers:

    [2097/6048] SOLINK ./lib_angle_unittests__library.cr.so
    FAILED: lib_angle_unittests__library.cr.so lib_angle_unittests__library.cr.so.TOC lib.unstripped/lib_angle_unittests__library.cr.so
    python "../../build/toolchain/gcc_solink_wrapper.py" --readelf="../../third_party/android_ndk/toolch...(too long)
    ld.lld: error: undefined symbol: glCreateShader
    >>> referenced by shader_utils.cpp
    >>>               angle_util_static/shader_utils.o:(CompileShader(unsigned int, char const*)) in archive obj/third_party/angle/libangle_util_static.a
    
    ld.lld: error: undefined symbol: glShaderSource

Original change's description:
> Reland "Add more test_utils functions."
> 
> 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.
> 
> 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: I6a2c1e7b585a13ca846759f32da0777c00d7f7e6
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1869541
> Commit-Queue: Jamie Madill <jmadill@chromium.org>
> Reviewed-by: Jamie Madill <jmadill@chromium.org>

TBR=ynovikov@chromium.org,jonahr@google.com,jmadill@chromium.org

Change-Id: I975b2214411906cb981bffa04fa50e0a65ff8b4e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:1015810, angleproject:3162
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1870811Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>