Compile libsurfaceflinger with Clang and -std=c++11 [DO NOT MERGE]

This is necessary to use C11/C++11 stdlib atomics, which the next
change will do. This change also fixes a couple bits of syntax that
both GCC and Clang refuse to compile in -std=c++11 mode.

Change-Id: Ia14d9d6b537a3bb106c23e19a277e48be180754c