Export of internal Abseil changes

--
62de74cdadc450a28eaa61a2db0912c97c8004dd by Abseil Team <absl-team@google.com>:

Move "internal/flag.*" files to the "internal" build target.

PiperOrigin-RevId: 268301646

--
72cd87aebd52fa7e7ee7cff0284f3761dd490945 by CJ Johnson <johnsoncj@google.com>:

Silences incorrect test failure for InlinedVector in MSVC debug mode.

PiperOrigin-RevId: 268234003
GitOrigin-RevId: 62de74cdadc450a28eaa61a2db0912c97c8004dd
Change-Id: I6b58e41561de6ac2e34cf5c1eedbf535dc468955