During refactoring of code, it has proved common to forget to
remove old symbols from the .syms file. While the Win32 linker
will complain about this, the Linux ELF linker does not. The
new test case validates that every symbol listed in the .syms
file actually exists in the built ELF libraries.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>