gnu: rapidcheck: Fix pkg-config libs.

Using rapidcheck as a dependency in a project currently results in a linker
error, because the pkg-config file is missing relevant linker flags.

* gnu/packages/patches/rapidcheck-fix-libs.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it here.
* gnu/packages/check.scm (rapidcheck)[patches]: Use it here.

gnu/local.mk

@@ -2077,6 +2077,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/qtwayland-cleanup-callbacks.patch	\
   %D%/packages/patches/ragel-char-signedness.patch		\
   %D%/packages/patches/randomjungle-disable-static-build.patch	\
+  %D%/packages/patches/rapidcheck-fix-libs.patch		\
   %D%/packages/patches/raptor2-heap-overflow.patch		\
   %D%/packages/patches/ratpoints-sturm_and_rp_private.patch	\
   %D%/packages/patches/ratpoison-shell.patch			\

gnu/packages/check.scm

@@ -3798,6 +3798,7 @@ provides a simple way to achieve this.")
          (sha256
           (base32 "1s2qva1amhs887jcdj12ppxk9kkfvy25xy7vzhkwb7rljr3gj713"))
          (modules '((guix build utils)))
+         (patches (search-patches "rapidcheck-fix-libs.patch"))
          (snippet
           #~(begin
               (make-file-writable "ext/CMakeLists.txt")

gnu/packages/patches/rapidcheck-fix-libs.patch

@@ -0,0 +1,27 @@
+From c4f558b0990571759fdaf976eb35ee1eb0d934a0 Mon Sep 17 00:00:00 2001
+From: Robert Hensing <robert@roberthensing.nl>
+Date: Tue, 25 Jun 2024 20:57:41 +0200
+Subject: [PATCH] Add -lrapidcheck to pkg-config module
+
+This adds the library to rapidcheck.pc, so that it doesn't have
+to be specified manually in projects that consume it.
+
+The other modules don't need it because they have rapidcheck in
+their Requires field.
+---
+ CMakeLists.txt | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index d55fdc51..046df2fd 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -128,7 +128,7 @@ set(PKG_CONFIG_DESCRIPTION_SUMMARY "C++ framework for property based testing ins
+ set(PKG_CONFIG_VERSION)
+ set(PKG_CONFIG_LIBDIR "\${prefix}/lib")
+ set(PKG_CONFIG_INCLUDEDIR "\${prefix}/include")
+-set(PKG_CONFIG_LIBS)
++set(PKG_CONFIG_LIBS "-L\${libdir} -lrapidcheck")
+ set(PKG_CONFIG_CFLAGS "-I\${includedir}")
+ 
+ configure_file(