Numerous additional variants were added to the Evergreen build (CDRIVER-3124). However, there are some which have unresolved issues and hence have been disabled.

suse12-s390x (CMake fails to build): https://evergreen.mongodb.com/task/libmongocrypt_suse12_s390x_build_and_test_and_upload_patch_6b78ecd6e75f77425918f51abe5336e860b5c12d_5ce406685623433868cabc3a_19_05_21_14_08_41
ubuntu1604-arm64 (CMake that is found is too old): https://evergreen.mongodb.com/task/libmongocrypt_ubuntu1604_arm64_build_and_test_and_upload_patch_6b78ecd6e75f77425918f51abe5336e860b5c12d_5ce406685623433868cabc3a_19_05_21_14_08_41
rhel-62-64-bit (Python too old): https://evergreen.mongodb.com/task/libmongocrypt_rhel_62_64_bit_build_and_test_and_upload_patch_fbb9f59bf32019373232dc1a1fd85a00d6ab95de_5ce414a9850e6169dbb20518_19_05_21_15_09_30
rhel-67-s390x (Python too old): https://evergreen.mongodb.com/task/libmongocrypt_rhel_67_s390x_build_and_test_and_upload_patch_fbb9f59bf32019373232dc1a1fd85a00d6ab95de_5ce414a9850e6169dbb20518_19_05_21_15_09_30

The failures need to be investigated and corrected, then the builds need to be re-enabled in the Evergreen configuration.