Steps performed:
1.
git clone https://github.com/libbitcoin/secp256k1.git
2.
cd secp256k1/
3.
git checkout schnorrsig
4.
./configure --prefix=/Users/Scott/Projects/LibBitcoin/secp256k1/OSX_BUILD --enable-module-schnorrsig --enable-tests --enable-experimental
5.
make -j4
6.
make install
7.
find OSX_BUILD -type f -print
**
OSX_BUILD/include/secp256k1_schnorrsig.h
OSX_BUILD/include/secp256k1_preallocated.h
OSX_BUILD/include/secp256k1.h
OSX_BUILD/lib/libsecp256k1.a
OSX_BUILD/lib/pkgconfig/libsecp256k1.pc
OSX_BUILD/lib/libsecp256k1.la
OSX_BUILD/lib/libsecp256k1.0.dylib
**