[asan] Improve moving of non-instrumented allocas

[asan] Improve moving of non-instrumented allocas

In r242510, non-instrumented allocas are now moved into the first basic block.  This patch limits that to only move allocas that are present *after* the first instrumented one (i.e. only move allocas up).  A testcase was updated to show behavior in these two cases.  Without the patch, an alloca could be moved down, and could cause an invalid IR.

Differential Revision: http://reviews.llvm.org/D11339

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242883 91177308-0d34-0410-b5e6-96231b3b80d8