Don’t use DYLD_INSERT_LIBRARIES with a system executable

Don’t use DYLD_INSERT_LIBRARIES with a system executable.

OS X 10.11 introduces System Integrity Protection. One facet of that
forbids code injection into system executables. A Crashpad test checks
that information can be recovered from dyld in early-launch crashes by
requesting dyld load a nonexistent library with DYLD_INSERT_LIBRARIES.
The executable was meaningless but a system-provided executable,
/usr/bin/true, was used for convenience.

This test hung on OS X 10.11 because DYLD_INSERT_LIBRARIES was ignored
for the system executable, and no crash occurred. The test waited for a
crash that would never come.

A custom no-op executable, crashpad_snapshot_test_no_op, is provided as
an executable that does work with DYLD_INSERT_LIBRARIES.

BUG=crashpad:41
TEST=crashpad_snapshot_test MachOImageAnnotationsReader.CrashDyld
R=rsesek@chromium.org

Committed: https://chromium.googlesource.com/crashpad/crashpad/+/5e8e72f91c73bff9dbdb8d44afb1ce48f694bc8e

[Mark Mentovai, 2015-08-05 19:56:36]

mark@chromium.org changed reviewers:
+ rsesek@chromium.org

[Robert Sesek, 2015-08-05 20:27:47]

LGTM

[Mark Mentovai, 2015-08-05 22:24:58]

Committed patchset #1 (id:1) manually as
5e8e72f91c73bff9dbdb8d44afb1ce48f694bc8e (presubmit successful).