enclave_common: add missing <algorithm> header for GCC 14 compat

[berrange]

When building with GCC 14, various c++ stdlib functions are undefined:

sgx_enclave_common.cpp: In function ‘void* get_enclave_base_address_from_address(void*)’: sgx_enclave_common.cpp:164:23: error: ‘upper_bound’ is not a member of ‘std’; did you mean ‘lower_bound’?
  164 |     auto upper = std::upper_bound(s_enclave_base_address.begin(), s_enclave_base_address.end(), (uint64_t)target_address);
      |                       ^~~~~~~~~~~
      |                       lower_bound
sgx_enclave_common.cpp: In function ‘void* enclave_create_ex(void*, size_t, size_t, uint32_t, const void*, size_t, uint32_t, const void**, uint32_t*)’:
sgx_enclave_common.cpp:790:14: error: ‘sort’ is not a member of ‘std’; did you mean ‘qsort’?
  790 |         std::sort(s_enclave_base_address.begin(), s_enclave_base_address.end());
      |              ^~~~
      |              qsort
sgx_enclave_common.cpp: In function ‘bool enclave_delete(void*, uint32_t*)’:
sgx_enclave_common.cpp:1255:43: error: ‘remove’ is not a member of ‘std’; did you mean ‘move’?
 1255 |         s_enclave_base_address.erase(std::remove(s_enclave_base_address.begin(), s_enclave_base_address.end(), (uint64_t)base_address),
      |                                           ^~~~~~
      |                                           move

These stdlib functions are provided by bits/stl_algo.h, and prior to GCC 14, the <functional> header would pull in stl_algo.h.

With GCC 14, the <functional> header was changed to only pull in stl_algobase.h.

We must now use <algorithm> to get these definitions, which should work on all versions of GCC.