ASN1 tests: Match "Empty INTEGER" with the actual library behavior

mbedtls_asn1_get_int() and mbedtls_asn1_get_mpi() behave differently
on an empty INTEGER (0200). Don't change the library behavior for now
because this might break interoperability in some applications. Write
a test function that matches the library behavior.
diff --git a/tests/suites/test_suite_asn1parse.data b/tests/suites/test_suite_asn1parse.data
index c5d9136..e917241 100644
--- a/tests/suites/test_suite_asn1parse.data
+++ b/tests/suites/test_suite_asn1parse.data
@@ -164,8 +164,7 @@
 get_boolean:"020101":0:MBEDTLS_ERR_ASN1_UNEXPECTED_TAG
 
 Empty INTEGER
-depends_on:SUPPORT_NEGATIVE_INTEGERS
-get_integer:"0200":"":MBEDTLS_ERR_ASN1_INVALID_LENGTH
+empty_integer:"0200"
 
 INTEGER 0
 get_integer:"020100":"0":0