[sanitizer] [SystemZ] Implement internal_mmap.
[sanitizer] [SystemZ] Implement internal_mmap.

mmap on s390 is quite a special snowflake: since it has too many
parameters to pass them in registers, it passes a pointer to a struct
with all the parameters instead.

Differential Revision: http://reviews.llvm.org/D18889

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@266295 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt