Fix stack overflow in unit-core/test-api.c (#3125)
Fix stack overflow in unit-core/test-api.c (#3125)

We have to use jerry_get_string_size() to get the necessary buffer
size instead of jerry_get_string_length() and jerry_json_stringify().

JerryScript-DCO-1.0-Signed-off-by: Csaba Osztrogonác oszi@inf.u-szeged.hu
bzsolt/jerryscript,akosthekiss/jerryscript,zherczeg/jerryscript,akosthekiss/jerryscript,robertsipka/jerryscript,akosthekiss/jerryscript,zherczeg/jerryscript,jerryscript-project/jerryscript,robertsipka/jerryscript,akosthekiss/jerryscript,zherczeg/jerryscript,dbatyai/jerryscript,dbatyai/jerryscript,robertsipka/jerryscript,dbatyai/jerryscript,bzsolt/jerryscript,bzsolt/jerryscript,jerryscript-project/jerryscript,robertsipka/jerryscript,jerryscript-project/jerryscript,dbatyai/jerryscript,akosthekiss/jerryscript,robertsipka/jerryscript,jerryscript-project/jerryscript,zherczeg/jerryscript,bzsolt/jerryscript,bzsolt/jerryscript,zherczeg/jerryscript,robertsipka/jerryscript,jerryscript-project/jerryscript,dbatyai/jerryscript