MONGOCRYPT-775 make tester object static (#983)

Keep the large `tester` object off of the stack to address observed segfaults on Windows when increasing TEST_DATA_COUNT

Author: kevinAlbs

test/test-mongocrypt.c

@@ -915,7 +915,7 @@ static void test_tmp_bsonf(_mongocrypt_tester_t *tester) {
 bool _aes_ctr_is_supported_by_os = true;
 
 int main(int argc, char **argv) {
-    _mongocrypt_tester_t tester = {0};
+    static _mongocrypt_tester_t tester = {0};
     int i;
 
     TEST_PRINTF("Pass a list of patterns to run a subset of tests.\n");

test/test-mongocrypt.h

@@ -47,7 +47,6 @@ typedef enum tester_mongocrypt_flags {
 } tester_mongocrypt_flags;
 
 /* Arbitrary max of 2148 instances of temporary test data. Increase as needed.
- * TODO(MONGOCRYPT-775) increasing further (e.g. 3000+) causes a segfault on Windows test runs. Revise.
  */
 #define TEST_DATA_COUNT 2148