Consistently check 'IsCode' when allocating sections in RuntimeDyld (via
findOrEmitSection).

Vaidas Gasiunas's patch, r201259, fixed one instance where we were always
allocating sections as text. This patch fixes the remaining buggy call sites.

No test case: This isn't breaking anything that I know of, it's just
inconsistent.

<rdar://problem/15943542>



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201605 91177308-0d34-0410-b5e6-96231b3b80d8