Add missing dumpfile.cc to leveldatabase target in GN build.

Add missing dumpfile.cc to leveldatabase target in GN build.

This was found by looking at the output of gyp_flag_compare step in
http://build.chromium.org/p/chromium.linux/builders/Linux%20GN%20%28dbg%29/builds/24157/steps/gyp_flag_compare/logs/stdio

Tested on Linux with the following command lines:

$ gn gen out-gn
$ ninja -C out-gn leveldatabase
$ touch third_party/leveldatabase/src/db/dumpfile.cc
$ ninja -C out-gn leveldatabase

BUG=461019
TEST=see above
R=cmumford@chromium.org
TBR=brettw@chromium.org

CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:android_chromium_gn_compile_dbg,android_chromium_gn_compile_rel;tryserver.chromium.win:win8_chromium_gn_rel,win8_chromium_gn_dbg;tryserver.chromium.mac:mac_chromium_gn_rel,mac_chromium_gn_dbg

Committed: https://crrev.com/8a33c992e0a969f8ec7584da579980dba660e376
Cr-Commit-Position: refs/heads/master@{#322962}

[tfarina, 2015-03-28 14:09:19]

PTAL!

[cmumford, 2015-03-30 16:47:25]

https://codereview.chromium.org/1044613002/diff/1/build/secondary/third_party...
File build/secondary/third_party/leveldatabase/BUILD.gn (right):

https://codereview.chromium.org/1044613002/diff/1/build/secondary/third_party...
build/secondary/third_party/leveldatabase/BUILD.gn:37: "src/db/dumpfile.cc",
Do we need src/include/leveldb/dumpfile.h too?

[tfarina, 2015-03-30 19:16:24]

PTAL

https://codereview.chromium.org/1044613002/diff/1/build/secondary/third_party...
File build/secondary/third_party/leveldatabase/BUILD.gn (right):

https://codereview.chromium.org/1044613002/diff/1/build/secondary/third_party...
build/secondary/third_party/leveldatabase/BUILD.gn:37: "src/db/dumpfile.cc",
On 2015/03/30 16:47:25, cmumford wrote:
> Do we need src/include/leveldb/dumpfile.h too?

We don't, but yeah, included.

[cmumford, 2015-03-30 19:18:04]

lgtm

[tfarina, 2015-03-30 23:51:08]

TBRing Brett for this.

[tfarina, 2015-03-30 23:51:21]

The CQ bit was checked by tfarina@chromium.org

[commit-bot: I haz the power, 2015-03-30 23:52:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1044613002/40001

[commit-bot: I haz the power, 2015-03-31 02:39:27]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-03-31 02:40:10]

Patchset 3 (id:??) landed as
https://crrev.com/8a33c992e0a969f8ec7584da579980dba660e376
Cr-Commit-Position: refs/heads/master@{#322962}