[asan] fix dlclose-test to work with non-4K pages. Properly disable interface_symbols_linux on non-x86

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@182461 91177308-0d34-0410-b5e6-96231b3b80d8
[asan] attempting to fix the debian bot (on ubuntu the test builds; on debian it complains that _SC_PAGESIZE is unknown)

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@182462 91177308-0d34-0410-b5e6-96231b3b80d8