When creating function Symbols for functions that were defined in LLVM bitcode for the standard library, if any of the function parameters are integer types, create two ispc-side Symbols: one where the integer types are all signed and the other where they are all unsigned. This allows us to provide, for example, both store_to_int16(reference int a[], uniform int offset, int val) as well as store_to_int16(reference unsigned int a[], uniform int offset, unsigned int val). functions.
Added some additional tests to exercise the new variants of these.
Also fixed some cases where the __{load,store}_int{8,16} builtins would read from/write to memory even if the mask was all off (which could cause crashes in some cases.)
were expecting vector-width-aligned pointers where in point of fact,
there's no guarantee that they would have been in general.
Removed the aligned memory allocation routines from some of the examples;
they're no longer needed.
No perf. difference on Core2/Core i5 CPUs; older CPUs may see some
regressions.
Still need to update the documentation for this change and finish reviewing
alignment issues in Load/Store instructions generated by .cpp files.
