Add assertion checks for cases where buffers are greater than 2^31 -1.
Halide currently does not correctly handle all cases where a loop extent
or buffer size is greater than 2^31 -1 .
Merge branch 'master' into overflow_checks
Style cleanup. Add HalideRuntime.h as a dependency for tests as it is
good to include it to get type checking on routines delcared therein.
Merge branch 'master' into overflow_checks
Fix compiler warnings (int -> size_t)
Add user_context to halide_printf call
When vectorizing allocation, new dimension comes first

The ordering of dimensions in an allocate currently doesn't matter.
But if it ever does, it will be innermost first.
Merge branch 'overflow_checks'