On 32 bit platforms tv_nsec is a signed long while the FUSE setattr
arguments provide nanoseconds as uint32_t. C++17 treats uint32_t -> long
in a brace initializer as a narrowing conversion and rejects it on ILP32
targets. This surfaced when building on FreeBSD i386 with clang 19 where
the compiler refused the list initialization of struct timespec.
Add explicit static_cast<long>() for the nsec fields to make the
conversion intentional and portable. This avoids build failures on i386
while leaving 64 bit builds unchanged.
* Use concurrent_flat_map to build a global cache rather than per
thread.
* Create global maintanence thread manager for clearing unused cache
entries.
Emanuel Haupt