Add pkg-config file

[Chocobo1]

• Provide project information to autotools
• Add pkg-config file

Resolves #65.

The generated libbacktrace.pc would look like this:

prefix=/usr
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir=${prefix}/include

Name: libbacktrace
Description: A C library that may be linked into a C/C++ program to produce symbolic backtraces
URL: https://github.com/ianlancetaylor/libbacktrace
Version: 1.0
Cflags: -I${includedir}
Libs: -L${libdir} -lbacktrace

Note that the autotools scripts need to be regenerated and I consider it would be better done by the project maintainers.

[fsimonis]

Can we have this feature please? 🙏

This would greatly simplify the life of packagers and users alike!

[codeinred]

Boosting because this would be a nice feature!

[clopez]

+2 for this.. please this is something basic for any library