installd: avoid vector<const T>

A container of const T uses std::allocator<const T>, which was an
undocumented libc++ extension that has been removed. See
llvm.org/PR96319.

Bug: http://b/349681543
Test: m installd_dexopt_test
Test: m MODULES-IN-frameworks-native
Change-Id: Ib4bdefbfd0d5ab5802d360253daeb697124a3128