NaCl: Remove the IRT's Gyp dependency on libsrpc

NaCl: Remove the IRT's Gyp dependency on libsrpc

Since I removed the IRT's calls to NaClSrpcModuleInit() and
NaClPluginLowLevelInitializationComplete(), the IRT no longer depends
on SRPC.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3864
TEST=build

Committed: https://crrev.com/65a326a734d413e2124c6782b2e32a81ceca74c1
Cr-Commit-Position: refs/heads/master@{#313664}

[Mark Seaborn, 2015-01-28 16:13:52]

mseaborn@chromium.org changed reviewers:
+ teravest@chromium.org

[teravest, 2015-01-28 16:14:59]

lgtm

[Mark Seaborn, 2015-01-29 04:10:30]

The CQ bit was checked by mseaborn@chromium.org

[commit-bot: I haz the power, 2015-01-29 04:10:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/878623004/1

[commit-bot: I haz the power, 2015-01-29 04:14:50]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-29 04:16:08]

Patchset 1 (id:??) landed as
https://crrev.com/65a326a734d413e2124c6782b2e32a81ceca74c1
Cr-Commit-Position: refs/heads/master@{#313664}

[Mark Seaborn, 2015-02-05 18:08:20]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/901053008/ by mseaborn@chromium.org.

The reason for reverting is: SRPC will be required by an upcoming NaCl change..