Made initialization of halide thread pool thread-safe.
Made initialization of halide thread pool thread-safe.


Former-commit-id: a62a3d52f97551256e828610c493fd4c438ebf74
Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide