[tsan] reduce the size of stack frame in MapRodata to please gcc 4.8.2
[tsan] reduce the size of stack frame in MapRodata to please gcc 4.8.2

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@199200 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