As recommended by the CMake docs, let's tolerate systems or setups that
don't have backtrace(3) in the `<execinfo.h>` header file, such as those
using libbacktrace directly.
The backtrace execinfo API takes the number of addresses the result
buffer can hold instead of its size, for some reason. Previously
backtraces larger than 256 frames deep would write past the end of the
result buffer.
While macOS backtrace(3) puts a space directly after the mangled symbol
name, some versions of glibc put a + directly after it. This new logic
accounts for both situations when trying to demangle.
Co-Authored-By: Andreas Kling <kling@serenityos.org>
On platforms that support it, enable using ``<execinfo.h>`` to get
backtrace(3) to dump a backtrace on assertion failure. This should make
debugging things like WebContent crashes in Lagom much easier.
Just because we may compile serenity with or without NDEBUG doesn't
mean that consuming projects or Ports will share the setting.
Always define the custom assertion function so that we don't have to
keep the same debug settings between all projects.
Until now, VERIFY() failures would just cause a __builtin_trap() in
release builds, which made them a bit too harsh. This commit adds an
out-of-line helper function that prints the error before trapping.
