To avoid priority conflicts with the WiFi hardware driver thread which has priority of 1, the default thread priority of lwIP's TCP/IP thread is decreased to 2.
The option value length of Ethernet addresses can be more than 6 byte in lwIP. Therefore, the max_len parameter is check to be greater than or equal to ETHERNET_ADDR_LEN.
Module esp_idf_heap is enabled in cpu/esp32/Makefile.dep depending on other modules. Since cpu/esp32/Makefile.dep is read after cpu/esp32/Makefile.include, the conditional definition of the linker options for the wrapper functions had to be moved from cpu/esp32/Makefile.include to cpu/esp32/Makefile.dep.
If module esp_idf_heap is used, the memory management functions _malloc_r, _realloc_r, _calloc_r and _free_r have to be overridden by wrapper functions to use the heap_* functions of module _esp_idf_heap. However, this can lead to multiple symbol errors for these functions for some applications. To solve this symbol conflict, _malloc_r, _realloc_r, _calloc_r and _free_r functions are renamed to __wrap_* and the linker options are extended by -Wl,-wrap option when module esp_idf_heap is used.
When standard C libraries are added to BASELIBS to group them together with all other modules, there are multiple definitions for the putchar function. The one that is defined writing to the UART as standard output and the one that is provided by the standard C libraries. To solve this symbol conflict, putchar and getchar functions that use the UART as standard output/input are renamed to __wrap_putchar and __wrap_getchar and the linker options are extended by -Wl,-wrap option.
When linking an application, symbol pthread_setcancelstate is not known in standard C libraries, even if the pthread module is linked. This is because the pthread module is grouped with all other modules, but not with the default C libraries when they are added to LINK_FLAGS. Therefore, standard C libraries have to be added also to BASELIBS to group them with all other modules.
Fixes the problem that the compilation of an applications can throw unknown symbol errors for functions that aren't use at all. Thus, it is possible to remove the warning for unknown symbols and the compilation can abort if there are real unknown symbols.
