Header fix for trunk llvm.
Remove all use of stacksave/stackrestore intrinsics

They seemed to be tripping up NaCl. I've been burned by them too many times
now. Replaced them all with allocas at the function entrypoint.
Don't use inline assembly when compiling for NaCl.
Fix for trunk llvm
Merge branch 'master' into rvar_reorder
Remove trivial for loops earlier.
Bugfix in prefix matching in bounds inference.
Use a different delimiter for renaming inlined reductions.

The previous one confused the code that finds loop levels to inject
realizations.
Only check for recursive calls that are actual Halide calls.
Catch name collisions in allocations.
Avoid name collisions in allocations
Allow Func::bound to propogate upwards in bounds inference.
Updated vectorize_too_little error test

vectorizing by 1 is actually ok.