do not error out on generic-gnu + --enable-shared

If you build with --enabled-shared on a Linux arch not explicitly
listed, the configure script will abort because it didn't detect
"linux" in the fallback generic-gnu tuple.

Since this is the fallback tuple and people are passing
--enable-shared, assume the user knows what they're in for.

Change-Id: Ia35b657e7247c8855e3a94fca424c9884d4241e3
1 file changed