Fix 'errno' redefinition issue for GCC >= 10

[leszekgrzegorek]

Since GCC version 10 the global uninitialized variables go into .bss instead of .common, i.e. the -fno-common has became the default. This way linking stage ends up with 'errno' redefinition error because both nano-libc and libc already provide it. The Middlewares/Third_Party/LwIP/src/include/lwip/errno.h already provide the mechanism to either use the library based symbol or custom one by 'errno' macro definition.

[ASELSTM]

ST Internal Reference: 125015

[TOUNSTM]

Fixed in abbf9ca1b36c9abdb9339e86f0b7b2f4e79edc35