This demo consists of
1. An user-friendly library for getting Intel Attestation Service (IAS) report.
2. A application that uses this library to get IAS report.
This demo requires obtaining service provider certificate/ID from Intel.
This commit makes the toolchain easier to use in two folds:
1. When compiling C/C++ source files, no need to add "-fPIC -pie" flags manually;
2. When running executables generated by the Occlum toolchain on Linux, no
need to set the `LD_LIBRARY_PATH` manually.
