Fix mongo-c-driver version compatibility check tests

[eramongodb]

Followup to #1379 and #1416.

Despite #1379 including comments implying the patch version number is only checked when the minor version numbers are equal following a suggestion describing exactly this scenario, the CHECKED_IF conditions do not actually do as described. This bug is exposed by #1416 (2.1.0-dev vs. 2.0.2):

src/bsoncxx/test/private/bson_version.cpp:62: FAILED:
  CHECK( bson_get_micro_version() >= expect[2] )
with expansion:
  0 >= 2
with message:
  expect_str := "2.0.2"

This PR fixes the version compat test cases to actually only compare the patch version numbers when the minor version numbers compare equal. The "mongoc version numbers" test case was also incorrectly calling bson_get_micro_version instead of mongoc_get_micro_version.

src/bsoncxx/test/private/bson_version.cpp:63: FAILED - but was ok:
  CHECKED_IF( minor == expect[1] )
with expansion:
  1 == 0
with message:
  expect_str := "2.0.2"