CrashReporter: Fix compilation with musl libc

[earboxer]

It can be assumed this doesn't function correctly: my 'configuration does not support execinfo.h', so I have no backtrace to test against

Describe your PR, what does it fix/add?

Fixes compilation with musl libc, which does not include dladdr1.

Is there anything you want to mention? (unchecked code, possible bugs, found problems, breaking compatibility, etc.)

https://github.com/hyprwm/Hyprland/commit/3d9ca6381df1cdbf1731d7e2b39ea3f7574fce1e#commitcomment-138447420

I used #ifdef __GLIBC__ (as I don't think musl libc defines anything). If there are other libc's which provide dladdr1, it should be added to that ifdef (but how many libc's are there? bionic doesn't include dladdr1, but uClibc does-- if anyone uses uClibc, they might want to change the ifdef to get better backtraces)

Is it ready for merging, or does it need work?