Tweak third_party/BUILD for FreeBSD.

Partial commit for third_party/*, see #10734.

Signed-off-by: Philipp Wollermann <philwo@google.com>

third_party/BUILD

@@ -469,6 +469,7 @@ UNNECESSARY_DYNAMIC_LIBRARIES = select({
     "//src/conditions:arm": "*.so *.jnilib *.dll",
     "//src/conditions:linux_aarch64": "*.so *.jnilib *.dll",
     "//src/conditions:linux_ppc": "*.so *.jnilib *.dll",
+    "//src/conditions:freebsd": "*.so *.jnilib *.dll",
     "//src/conditions:openbsd": "*.so *.jnilib *.dll",
     # Play it safe -- better have a big binary than a slow binary
     # zip -d does require an argument. Supply something bogus.