Added a triple to the test builtins-multiprecision.c.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172342 91177308-0d34-0410-b5e6-96231b3b80d8
Fixed spelling of test name: builtins-multipercision.c => builtins-multiprecision.c.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172343 91177308-0d34-0410-b5e6-96231b3b80d8
clang/test/CodeGen/builtins-multiprecision.c: Enhance for each test to run on theree targets, i686, amd64, win64.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172344 91177308-0d34-0410-b5e6-96231b3b80d8