debug: fix resource (de)allocation for Elf and Coff targets
With this change, it is now possible to safely call
`var di = std.debug.openSelfDebugInfo(gpa)`. Calling then
`di.deinit()` on the object will correctly free all allocated
resources.
Ensure we store the result of `mmap` with correct alignment.
28ca203b71Jakub Konka committed on 4/21/2022, 9:48:15 AMparent96c1314