Build libui and libgui with -std=c++1z

This works around an issue reported with address sanitizer involving
std::shared_ptr<FenceTime> instances created by pre-C++17 compiled code,
and destroyed by C++17 compiled SurfaceFlinger.

The address sanitizer was complaining that there was a new/delete
alignment mismatch, where the instances were allocated with default
alignment, and destroyed with an 8-byte alignment requirement.

Starting with C++17, new and delete now have versions that take an
std::align_val_t argument that indicates the alignment of the
allocation. The address sanitizer is verifying that the call to new
matches the call to delete, and reports an error if it does not.

The C++17 standard says that the compiler should behave in a way that is
backwards compatible. In this case, FenceTime declares class-specific
new and delete functions, and normally those would be used. Except that
the current libc++ version of std::shared_ptr does not! It instead uses
its own calls to allocate memory, and does a placement-new to actually
create the FenceTime instance it shares. Unfortunately the version of
new and delete called depends on whether it is compiled for C++17 or
not.

To make the address sanitizer happy, we can just build libui and libgui
with -std=c++1z, which as a bonus allows the class-specific new to be
removed.

(Reproducing the failure requires a not-yet submitted CL which adds test
coverage for composition calls, and another change to enable address
sanitizer on the unit test)

Bug: None
Test: atest libsurfaceflinger_unittest
Change-Id: I2321bbdbf64a8a068ba2b5ed73013ddd2fa6c32e