fix-tests
[libc] Add a simple StringStream class.
[libc][NFC] Add a death test API adaptation macro
[libc][NFC] add "LlvmLibc" as a prefix to all test names
[libc][Obvious] Use the correct StringView constructor in dirent_test.
[libc] Make the errno macro resolve to the thread local variable directly.
[libc] Add a few missing deps, includes, and fix a few typos.
[libc] Reset rounding mode after fsetround tests
[libc] Add imaxabs
[libc] Implement sinf function that is correctly rounded to all rounding modes.
[libc][NFC] Convert pthread tests which create threads to integration tests.
[libc] add rounding modes to printf float conv
[libc] fix strtofloatingpoint on rare edge case
[libc] Add a separate algorithm_test.
[libc][Obvious] Fix c++20-designator warnings for tests that use TmHelper.h.
[libc] Add implementation of POSIX lseek function.
[libc] Add dirent.h functions opendir, readdir, closedir and dirfd.