CDRIVER-720 iter should stay the same after bson_iter_recurse() (Correct its document)

Signed-off-by: A. Jesse Jiryu Davis <jesse@mongodb.com>

CDRIVER-1351 Handle parsing invalid base64 in $binary

Signed-off-by: A. Jesse Jiryu Davis <jesse@mongodb.com>

CDRIVER-1378: Accept NULL endptr in bson_ascii_strtoll()

CDRIVER-1403 fixed buffer overrun/read in bson_strndup

CDRIVER-1387 Fix MSVC syntax error in align

Implemented in the interest of consistency with strtoll().

Since test_bson_ascii_strtoll() was not testing any assignment to endptr, it can now pass NULL.

CDRIVER-1340 Serialize $binary and $type in the correct order

I'd thought specifying two symbol files with CMake's add_library would
merge their symbol tables. In fact the last file wins, so all symbols
must be included in single symbol file.