Merge bitcoin/bitcoin#31276: guix: scope pkg-config to Linux only

bcd82b1 Remove pkgconfig from toolchain file (TheCharlatan)
319a4e8 depends: drop sqlite pkgconfig file (fanquake)
a8fe1fd depends: better cleanup after fontconfig (fanquake)
17e79c9 depends: fully remove libtool archives from Qt build (fanquake)
8ca8565 guix: move pkg-config to Linux builds (fanquake)
e3e648c depends: drop pkg-config option from Qt build (fanquake)
0d185bd doc: update depends doc to prefer .cmake outputs (fanquake)

Pull request description:

  After #31181, `pkg-config` is no-longer needed for macOS or Windows Guix builds. It's still needed for Linux, as it's used by a Qt subdependency (fontconfig to find freetype). However we should also no-longer need it for Qt itself, when building using depends.

ACKs for top commit:
  TheCharlatan:
    ACK bcd82b1

Tree-SHA512: 89ae68281030d43fcb6c5c96429cd038a21f13a8ca19ea828ada47e8f9f0aa7407854a67c9003652817e47ab9565573b7028342e3e11bb1cca1d823c483081cd

contrib/guix/manifest.scm

@@ -511,7 +511,6 @@ inspecting signatures in Mach-O binaries.")
         gcc-toolchain-12
         cmake-minimal
         gnu-make
-        pkg-config
         ;; Scripting
         python-minimal ;; (3.10)
         ;; Git
@@ -527,6 +526,7 @@ inspecting signatures in Mach-O binaries.")
                  osslsigncode))
           ((string-contains target "-linux-")
            (list bison
+                 pkg-config
                  (list gcc-toolchain-12 "static")
                  (make-bitcoin-cross-toolchain target)))
           ((string-contains target "darwin")

depends/packages.md

@@ -153,8 +153,8 @@ Most autotools projects can be properly staged using:
 ## Build outputs:
 
 In general, the output of a depends package should not contain any libtool
-archives. Instead, the package should output `.pc` (`pkg-config`) files where
-possible.
+archives or `.pc` (`pkg-config`) files. Instead, the package should output
+`.cmake` (CMake) files where possible.
 
 From the [Gentoo Wiki entry](https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Handling_Libtool_Archives):
 

depends/packages/fontconfig.mk

@@ -29,5 +29,5 @@ define $(package)_stage_cmds
 endef
 
 define $(package)_postprocess_cmds
-  rm -rf var lib/*.la
+  rm -rf bin etc share var lib/*.la
 endef

depends/packages/qt.mk

@@ -10,7 +10,6 @@ $(package)_linguist_tools = lrelease lupdate lconvert
 $(package)_patches = qt.pro
 $(package)_patches += qttools_src.pro
 $(package)_patches += mac-qmake.conf
-$(package)_patches += fix_qt_pkgconfig.patch
 $(package)_patches += no-xlib.patch
 $(package)_patches += dont_hardcode_pwd.patch
 $(package)_patches += qtbase-moc-ignore-gcc-macro.patch
@@ -64,6 +63,7 @@ $(package)_config_opts += -no-mimetype-database
 $(package)_config_opts += -no-mtdev
 $(package)_config_opts += -no-openssl
 $(package)_config_opts += -no-openvg
+$(package)_config_opts += -no-pkg-config
 $(package)_config_opts += -no-reduce-relocations
 $(package)_config_opts += -no-schannel
 $(package)_config_opts += -no-sctp
@@ -84,7 +84,6 @@ $(package)_config_opts += -nomake examples
 $(package)_config_opts += -nomake tests
 $(package)_config_opts += -nomake tools
 $(package)_config_opts += -opensource
-$(package)_config_opts += -pkg-config
 $(package)_config_opts += -prefix $(host_prefix)
 $(package)_config_opts += -qt-libpng
 $(package)_config_opts += -qt-pcre
@@ -226,7 +225,6 @@ define $(package)_preprocess_cmds
   cp $($(package)_patch_dir)/qttools_src.pro qttools/src/src.pro && \
   patch -p1 -i $($(package)_patch_dir)/fix-macos-linker.patch && \
   patch -p1 -i $($(package)_patch_dir)/dont_hardcode_pwd.patch && \
-  patch -p1 -i $($(package)_patch_dir)/fix_qt_pkgconfig.patch && \
   patch -p1 -i $($(package)_patch_dir)/no-xlib.patch && \
   patch -p1 -i $($(package)_patch_dir)/qtbase-moc-ignore-gcc-macro.patch && \
   patch -p1 -i $($(package)_patch_dir)/memory_resource.patch && \
@@ -273,6 +271,6 @@ define $(package)_stage_cmds
 endef
 
 define $(package)_postprocess_cmds
-  rm -rf doc/ native/lib/ && \
-  rm -f lib/lib*.la
+  rm -rf doc/ native/lib/ lib/pkgconfig/ && \
+  rm -f lib/lib*.la lib/Qt5*.la
 endef

depends/packages/sqlite.mk

@@ -31,5 +31,6 @@ define $(package)_stage_cmds
 endef
 
 define $(package)_postprocess_cmds
+  rm -rf lib/pkgconfig && \
   rm lib/*.la
 endef

depends/toolchain.cmake.in

@@ -87,15 +87,6 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin" AND NOT CMAKE_HOST_APPLE)
   set(CMAKE_FRAMEWORK_PATH "@OSX_SDK@/System/Library/Frameworks")
 endif()
 
-
-# Customize pkg-config behaviour.
-cmake_path(APPEND CMAKE_FIND_ROOT_PATH "lib" "pkgconfig" OUTPUT_VARIABLE pkg_config_path)
-set(ENV{PKG_CONFIG_PATH} ${pkg_config_path})
-set(ENV{PKG_CONFIG_LIBDIR} ${pkg_config_path})
-unset(pkg_config_path)
-set(PKG_CONFIG_ARGN --static)
-
-
 # Set configuration options for the main build system.
 set(qt_packages @qt_packages@)
 if("${qt_packages}" STREQUAL "")