Add a dummy bn_is_zero C dependency to wrap BN_is_zero

This is necessary because on some architectures BN_is_zero
is a CPP macro, so trying to link against it in an `extern "C"`
block causes a linker error.

This also introduces a build command to Cargo to compile
the bn_is_zero wrapper.

1 files changed, 1 insertions, 0 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 4c61dd7e..4af5bac9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,6 +3,7 @@
 name = "openssl"
 version = "0.0.0"
 authors = ["Steven Fackler <[email protected]"]
+build = "make"
 
 [lib]