snappy does not provide a pkg-config

[lavoiesl]

Describe the bug
Because snappy does not install a pkgconfig file, you can't take snappy as a buildInput, packages will never find it.

To Reproduce

$ nix-shell -p snappy snappy.dev
[nix-shell:~]$ pkg-config --debug --libs snappy
Error printing enabled by default due to use of output options besides --exists, --atleast/exact/max-version or --list-all. Value of --silence-errors: 0
Error printing enabled
Adding virtual 'pkg-config' package to list of known packages
Looking for package 'snappy'
Looking for package 'snappy-uninstalled'
Package snappy was not found in the pkg-config search path.
Perhaps you should add the directory containing `snappy.pc'
to the PKG_CONFIG_PATH environment variable
No package 'snappy' found

Expected behavior

$ pkg-config snappy --libs
-L/nix/store/hknzbw87dnmz7zq0lf99vjf7bf2l2hps-snappy-1.1.7/lib -lsnappy
$ pkg-config snappy --cflags
-I/nix/store/z67qhiawswr2jq1p71r4f2987czx3slh-snappy-1.1.7-dev/include

Metadata

• system: "x86_64-darwin"
• host os: Darwin 19.0.0, macOS 10.15
• multi-user?: no
• sandbox: no
• version: nix-env (Nix) 2.3.1
• channels(seb): "nixpkgs-20.03pre197736.91d5b3f07d2"
• nixpkgs: /Users/seb/.nix-defexpr/channels/nixpkgs

Maintainer information:

attribute: snappy.dev
# a list of nixos modules affected by the problem
module:

cc @wkennington @viric

[lavoiesl]

I have opened a PR on the snappy codebase: google/snappy#86

It is waiting for review and then nixpkgs will need to be updated.

Note how the PR has to handle the absolute path being configured in cmake by nix

[lavoiesl]

google/snappy#86 has decided not to take the patch upstream, so I will work on adding the pkg-config file as part of the nix installation

[stale]

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