Memory management

Function	Target	#define location	Notes
`malloc`	`pvPortMalloc`	`component/common/api/platform/platform_stdlib.h`
`zalloc`	`os_zalloc` (ROM)		This is PROBABLY BROKEN. ROM disassembly shows it only does memset on a fixed memory range.
`zalloc`	`pvPortZalloc`	`arduino/realtek-ambz/cores/WVariant.h`	Custom implementation in `rtl_sys.cpp`
`calloc`	`os_calloc`	?	This one is not in ROM. I didn't dig any deeper into it.
`calloc`	`calloc_freertos`	`component/os/freertos/cmsis_os.h`	Probably not used
`calloc`	`__rtl_calloc_r` (ROM)		Not used, as I preferred to use FreeRTOS memory management.
`calloc`	`pvPortCalloc`	`arduino/realtek-ambz/cores/WVariant.h`	Custom implementation in `rtl_sys.cpp`
`realloc`	`pvPortRealloc`	`arduino/realtek-ambz/cores/WVariant.h`
`free`	`vPortFree`	`component/common/api/platform/platform_stdlib.h`

Underlined item means that it is defined and used in code.