fix-tests
[libc] Add Uint128 type as a fallback when __uint128_t is not available.
[libc] Make div test names unique
[libc] Add exit and atexit
[libc][NFC] Add a death test API adaptation macro
[libc][NFC] add "LlvmLibc" as a prefix to all test names
[libc] Fix exit not calling new handlers registered from a call to atexit in atexit handler
[libc] apply formatting to tests
[libc] add atoi, atol, and atoll
[libc] Enable string to integer conversion functions in the default build
[libc] Add implementations of div, ldiv, lldiv and imaxdiv.
[libc] fix strtofloatingpoint on rare edge case
[libc] Specify rounding mode for strto[f|d] tests
[libc] fix strtol returning the wrong length