floating point instrs in Windows release build our_vsnprintf

_From [derek.br...@gmail.com](https://code.google.com/u/117968039472581148324/) on August 20, 2010 16:22:35_

there are floating point instrs in the Windows release build of
our_vsnprintf

w/ Dr. Memory I once saw w/ -verbose 2 a STATUS_FLOAT_UNDERFLOW
(0xc0000093) exception on the fldz

there are no float instrs in debug build

I thought we used to have a build step that checked but can't find it now

dynamorio!our_vsnprintf+0x37 [e:\derek\dr\win32\opensource\core\io.c @ 219]:
219 7104efe7 d9ee fldz
219 7104efe9 8bbc2498000000 mov edi,[esp+0x98]
219 7104eff0 d9e8 fld1
219 7104eff2 dd0550150a71 fld qword ptr [dynamorio!_realbff0000000000000 (710a1550)]
219 7104eff8 dd0548150a71 fld qword ptr [dynamorio!_real (710a1548)]
219 7104effe eb02 jmp dynamorio!our_vsnprintf+0x52 (7104f002)

_Original issue: http://code.google.com/p/dynamorio/issues/detail?id=339_