Convert the production source files in src/ (69 .c/.cpp) and
test/jemalloc_test.h.in to list the headers they actually use, then
delete the umbrella. Three consolidated headers (peak_event.h,
prof_sys.h, sz.h) also gain explicit transitive includes.
Every translation unit now declares what it uses. A missing include
now fails at the failing file rather than silently working because
something upstream pulled in the world.
Header files are now self-contained, which makes the relationships
between the files clearer, and crucially allows LSP tools like `clangd`
to function correctly in all of our header files. I have verified that
the headers are self-contained (aside from the various Windows shims) by
compiling them as if they were C files – in a follow-up commit I plan to
add this to CI to ensure we don't regress on this front.
Existing backtrace implementations skip native stack frames from runtimes like
Python. The hook allows to augment the backtraces to attribute allocations to
native functions in heap profiles.