unix/mpconfigport.h: Enable MICROPY_PY_URE_SUB.
ure.sub() is very practical facility for string manipulation. Even despite
the fact that it adds 688 code bytes on x86 (32-bit), give up and add it to
teh baselibe unix config (so it will be enabled in all unix builds, except
minimal).
#define MICROPY_PY_UZLIB (1)
#define MICROPY_PY_UJSON (1)
#define MICROPY_PY_URE (1)
+#define MICROPY_PY_URE_SUB (1)
#define MICROPY_PY_UHEAPQ (1)
#define MICROPY_PY_UTIMEQ (1)
#define MICROPY_PY_UHASHLIB (1)
