drop bundled gflags from the checkout

The only code using gflags is google_crash_report_sender, and nothing
builds or tests that code currently.  Switch it over to using system
versions of gflags so we can drop the local prebuilts.  Tested local
builds by hand of the tool.

Bug: google-breakpad:360
Change-Id: I75d79b176468c948773079a54d87e70709feaf87
Reviewed-on: https://chromium-review.googlesource.com/665799
Reviewed-by: Mark Mentovai <mark@chromium.org>
Cr-Mirrored-From: https://chromium.googlesource.com/breakpad/breakpad
Cr-Mirrored-Commit: 6a4976483b1d5892905618254af65afa7d8baa83
3 files changed