[optimizing] Fold HTypeConversion of constants

While looking into optimizing long shifts on x86, I found that the
compiler wasn't folding HTypeConversion of constants.  Add simple
conversions of constants, taking care of float/double values
with NaNs and small/large values, ensuring Java conversion semantics.

Add checker cases to see that constant folding of HTypeConversion is

Ensure 422-type-conversion type conversion routiness don't get
inlined to avoid compile time folding.

Change-Id: I5a4eb376b64bc4e41bf908af5875bed312efb228
Signed-off-by: Mark Mendell <mark.p.mendell@intel.com>
6 files changed