Creating the build directory in `..` may be OK in a sandbox, but this
makes it unnecessarily annoying when trying to work with this in a
source-checkout.
Hence, move the `build/` directory into the source tree.
The nixpkgs-unstable channel's programs.sqlite was used to identify
packages producing exactly one binary, and these automatically added
to their package definitions wherever possible.
`mtrace(1)` is a small Perl script that interprets and provides
human-readable output for `malloc(3)` traces.
Even though this is actually part of `glibc` itself I decided to place
this into its own package. The main reason for this is that this script
has a runtime dependency on Perl which would complicate `stdenv`
bootstrapping since we'd have to compile another Perl that doesn't depend on
the bootstrap tools that is used as runtime dependency for the
stage2 glibc.
Since this is only a dev/debugging tool, splitting this up seemed like a
reasonable choice to me.
On a leaking C program, this can be used like this:
$ env MALLOC_TRACE=$(pwd)/trace ./a.out
$ ./result/bin/mtrace ./trace
Memory not freed:
-----------------
Address Size Caller
0x0000000001875690 0x4 at 0x401151
Closes#141924
