[PATCH 7/8] pkgs/libfyaml: fix pkg-config libs

[colbyt <colby@colbyt.com>]

The current nixpkgs libfyaml package can install a malformed Libs line
containing the tokens "none required".

AppStream consumes libfyaml.pc when building the Spectrum integration
closure, and those stray tokens make the link step fail before the VM
tests run.

Normalize the generated pkg-config file in postInstall until the pinned
nixpkgs package no longer needs the workaround.

Signed-off-by: colbyt <colby@colbyt.com>
---
 pkgs/overlay.nix | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/pkgs/overlay.nix b/pkgs/overlay.nix
index 66fea11..559e361 100644
--- a/pkgs/overlay.nix
+++ b/pkgs/overlay.nix
@@ -115,6 +115,13 @@
       }
   ));
 
+  libfyaml = super.libfyaml.overrideAttrs ({ postInstall ? "", ... }: {
+    postInstall = postInstall + ''
+      sed -i 's/ -lpthread   none required -lfyaml/ -lpthread -lfyaml/' \
+        "$dev/lib/pkgconfig/libfyaml.pc"
+    '';
+  });
+
   gtk3 = import ./gtk3 { inherit final super; };
 
   mailutils = super.mailutils.overrideAttrs (_: (
-- 
2.54.0