curl: fix detection by dependents

Install a pkg-config entry to staging so components can be detected when there's no `curl-config` available.

thirdparty/curl/CMakeLists.txt

@@ -11,6 +11,7 @@ list(APPEND PATCH_CMD COMMAND ${KO_PATCH} ${CMAKE_CURRENT_SOURCE_DIR}/ca_bundle.
 
 # Make sure the daisy-chain once again picks up our toolchain file...
 list(APPEND CMAKE_ARGS "-DCMAKE_TOOLCHAIN_FILE=${CMAKE_TCF}")
+list(APPEND CMAKE_ARGS "-DCMAKE_INSTALL_PREFIX=${INSTALL_DIR}")
 
 # Features.
 # TODO: Enable ZSTD support? We currently only use cURL for zsync2, so, obviously, not necessary right now…
@@ -51,7 +52,9 @@ set_libname(LIB ${LIB_SPEC})
 # Install shared lib.
 append_shared_lib_install_command(INSTALL_CMD BYPRODUCTS lib/${LIB} ${LIB_SPEC})
 
-# For pocketbook, add a symlink so dependent packages find our renamed version.
+# Even with after installing a patched pkg-config entry, we still need to add a symlink
+# with the canonical library name or the mess that is CMake's FindCURl module will fail
+# at detecting our renamed library…
 if(POCKETBOOK)
     list(APPEND INSTALL_CMD COMMAND ln -snf ${LIB} "${STAGING_DIR}/lib/libcurl${LIB_EXT}")
 endif()
@@ -65,6 +68,9 @@ append_headers_install_command(
     stdcheaders.h system.h typecheck-gcc.h urlapi.h websockets.h
 )
 
+# Install pkg-config entry (needed for curl components detection by CMake's FindCURl).
+append_install_commands(INSTALL_CMD BYPRODUCTS libcurl.pc DESTINATION "${STAGING_DIR}/lib/pkgconfig/")
+
 thirdparty_project(
     URL https://github.com/curl/curl/releases/download/curl-8_5_0/curl-8.5.0.tar.xz
     URL_MD5 3e9e5c2db494e7dbd4e7024b149021c9

thirdparty/curl/pocketbook_lib_rename.patch

@@ -11,3 +11,13 @@
  add_definitions(-DBUILDING_LIBCURL)
 
  configure_file(curl_config.h.cmake
+--- i/libcurl.pc.in
++++ w/libcurl.pc.in
+@@ -36,6 +36,6 @@ Name: libcurl
+ URL: https://curl.se/
+ Description: Library to transfer files with ftp, http, etc.
+ Version: @CURLVERSION@
+-Libs: -L${libdir} -lcurl @LIBCURL_NO_SHARED@
++Libs: -L${libdir} -lcurl_ko @LIBCURL_NO_SHARED@
+ Libs.private: @LIBCURL_LIBS@
+ Cflags: -I${includedir} @CPPFLAG_CURL_STATICLIB@