build for gdb on linux

build debug on linux for gdb

Building with this define enables additional
checks for standard library functions when
running gdb, and allows printing std::string.

R=halcanary@google.com

Bug: skia:
Change-Id: I7f2dc12336f9239443328f13264be7a6b285c4b5
Reviewed-on: https://skia-review.googlesource.com/140786
Commit-Queue: Cary Clark <caryclark@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-on: https://skia-review.googlesource.com/141083
Commit-Queue: Cary Clark <caryclark@skia.org>
3 files changed