Needed because libtomcrypt expects this symbol to be available
https://github.com/libtom/tomsfastmath/commit/81530c207da8b3a43867da14df7d79d2cdf96978.patch
--- a/libtfm.symbols
+++ b/libtfm.symbols
@@ -16,6 +16,7 @@ fp_gcd
 fp_ident
 fp_invmod
 fp_isprime
+fp_isprime_ex
 fp_lcm
 fp_lshd
 fp_mod