The problem is that time_t is signed, and the original code relied on the
fact that (X + c < X) in case of overflow for c >= 0. Unfortunately, this
condition is only guaranteed by the standard for unsigned arithmetic, and
the gcc 4.4.0 optimizer did completely remove the corresponding test from
the code. This resulted in a missing boundary check, and an infinite loop.
The problem is solved by testing explicitely for TIME_T_MIN and TIME_T_MAX
in the loop that uses this.
Also fix increment_overflow and long_increment_overflow which were buggy
for exactly the same reasons.
Also remove some compiler warnings.
Note: a similar fix was performed in bionic/libc
