Build libffi with -fvisibility=hidden.

We're linking libffi statically. Without visibility=hidden, then can
result in name clashes with other versions of libffi that are pulled in
as transitive dependencies of random other libraries.

truffle/mx.truffle/mx_truffle.py

@@ -1571,7 +1571,7 @@ def getArchivableResults(self, use_relpath=True, single=False):
             configure_args = ['--disable-dependency-tracking',
                               '--disable-shared',
                               '--with-pic',
-                              ' CFLAGS="{}"'.format(' '.join(['-g', '-O3'] + (['-m64'] if mx.get_os() == 'solaris' else []))),
+                              ' CFLAGS="{}"'.format(' '.join(['-g', '-O3', '-fvisibility=hidden'] + (['-m64'] if mx.get_os() == 'solaris' else []))),
                               'CPPFLAGS="-DNO_JAVA_RAW_API"',
                              ]