Implement floatsitf, floatunstfsi, which perform
(signed/unsigned)integer to quad-precision conversion.

Submitted by GuanHong Liu.

Differential Revision: http://reviews.llvm.org/D2805


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@217901 91177308-0d34-0410-b5e6-96231b3b80d8
[sanitizer]  Fix global constructor warning in sanitizer; patch by Samuel F Antao

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@217904 91177308-0d34-0410-b5e6-96231b3b80d8