Compile runtime at O3 to ensure elimination of dead globals
Compile runtime at O3 to ensure elimination of dead globals

This is necessary to ensure that dead globals are eliminated - inline
linkage things become comdats, which breaks cross compilation to OS X.
The default set of optimization passes differs on Windows and Linux, so
I'm just turning on all optimizations on both platforms. CMakeFile
change to follow in next commit.


Former-commit-id: d2ebe6ef606526f7656962ee28ab1d077911fad3
darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide