[libcxx] [test] Fix MSVC warnings, null pointer deref.

test/std/algorithms/alg.modifying.operations/alg.generate/generate_n.pass.cpp
Silence MSVC warning C4244. This is expected when passing
floating-point values for size.

test/std/utilities/template.bitset/bitset.members/to_ullong.pass.cpp
test/std/utilities/template.bitset/bitset.members/to_ulong.pass.cpp
Avoid MSVC "warning C4293: '<<': shift count negative or too big,
undefined behavior". MSVC sees (1ULL << N) and warns - being guarded
by const bool canFit is insufficient. A small change to the code
avoids the warning without the need for a pragma.

Remove a spurious printf() declaration from to_ullong.pass.cpp.

Change ULL to UL in to_ulong.pass.cpp. The ULL suffix was
probably copy-pasted.

test/std/utilities/tuple/tuple.general/ignore.pass.cpp
Use LIBCPP_STATIC_ASSERT for consistency with other files.

test/support/container_test_types.h
Fix a null pointer dereference, found by MSVC /analyze
warning C6011 "Dereferencing NULL pointer 'm_expected_args'."

Fixes D41030.

llvm-svn: 320535