Fix a compiler warning

fil_space_verify_crypt_checksum(): Add a dummy return statement
in case memory is corrupted and innodb_checksum_algorithm has
an invalid value.

storage/innobase/fil/fil0crypt.cc

@@ -2630,4 +2630,7 @@ bool fil_space_verify_crypt_checksum(const byte* page, ulint zip_size)
 		return checksum == buf_calc_page_crc32(page)
 			|| checksum == buf_calc_page_new_checksum(page);
 	}
+
+	ut_ad(!"unhandled innodb_checksum_algorithm");
+	return false;
 }

storage/xtradb/fil/fil0crypt.cc

@@ -2630,4 +2630,7 @@ bool fil_space_verify_crypt_checksum(const byte* page, ulint zip_size)
 		return checksum == buf_calc_page_crc32(page)
 			|| checksum == buf_calc_page_new_checksum(page);
 	}
+
+	ut_ad(!"unhandled innodb_checksum_algorithm");
+	return false;
 }