define better name for sgxcclib and rename it

[bvavala]

sgxcclib is used in the respective enclaves (in ecc_enclave and tlcc_enclave) with a common part in common/sgxcclib. A better name would probably include an fpc_ and/or an enclave prefix, and or a _t/_u to distinguish the trusted and untrusted functions -- though sgxcclib is used in untrusted space, essentially as an enclave wrapper.