Description: when the number is the minimum negative value of long long
type, the ubsan build raises a runtime error.

In my_strtoll10_mb2(), it uses one unsigned value to hold a negative
number's abs value. If the number is the minimum negative value of long
long type (-9223372036854775808), its abs value (9223372036854775808)
exceeds the maximum positive value of long long type (9223372036854775807).

Fix: return LLONG_MIN if its abs value equals the maximum positive value.

Change-Id: I9a7a4df1596a586b1bfab2a3725a9a6998969be7