Ignore multiple symbol definition errors.

libc and libc++ both define std::nothrow. libc's is a private symbol,
but this still causes issues when linking libc.a and libc++.a, since
private isn't effective until it has been linked. To fix this, just
allow multiple symbol definitions for the static tests.

Change-Id: Idbf19fefda47298c39360e3f5b6242b0b1a52fcc