[ion-c-sys] Adds lib64 Path to Build Script

[almann]

On RHEL/CentOS/Amazon Linux the install target on x86-64 installs to lib64 path, on other platforms (including Windows and macOS) this is lib, we need to add lib64 to the build script.

This can be reproduced with the following docker image with a checkout of the repository.

# Build:
# docker build -t ion-rust-al2 --build-arg USER_ID=$(id -u) --build-arg GROUP_ID=$(id -g) $(pwd)
#
# Run:
# docker run --interactive --tty --rm --mount type=bind,source="$(pwd)",target=/workspace ion-rust-al2

FROM amazonlinux:2

ARG USER_ID
ARG GROUP_ID
ARG WORKSPACE_DIR=/workspace

RUN yum -y install clang llvm-devel git gcc gcc-c++ wget curl tar make
RUN wget --quiet  https://github.com/Kitware/CMake/releases/download/v3.18.3/cmake-3.18.3-Linux-x86_64.sh
RUN sh ./cmake-3.18.3-Linux-x86_64.sh --skip-license --prefix=/usr/local

RUN groupadd --gid $GROUP_ID user
RUN useradd -l --uid $USER_ID --gid $GROUP_ID user
RUN mkdir $WORKSPACE_DIR && chown $USER_ID.$GROUP_ID $WORKSPACE_DIR

USER user
WORKDIR $WORKSPACE_DIR

RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | /bin/sh -s -- -y

ENV PATH=/home/user/.cargo/bin:$PATH

CMD cargo clean && cargo build