autoen: Fix cross build

See comments for details. Patch can be removed whend version is bumped.

pkgs/development/tools/misc/autogen/default.nix

@@ -11,6 +11,22 @@ stdenv.mkDerivation rec {
 
   outputs = [ "bin" "dev" "lib" "out" "man" "info" ];
 
+  patches = [
+    # Temporary, so builds with a prefixed pkg-config (like cross builds) work.
+    #
+    # https://savannah.gnu.org/support/?109050 was supposed to fix this, but
+    # the generated configure script mysteriously still contained hard-coded
+    # pkg-config. I tried regenerating it, but that didn't help. Only
+    # https://git.savannah.gnu.org/cgit/autogen.git/commit/?h=5cbe233387d7f7b36752736338d1cd4f71287daa,
+    # in the next release, finally fixes this, by getting rid of some
+    # metaprogramming of the autoconf m4 metaprogram! There evidentally was
+    # some sort escaping error such that the `PKG_CONFIG` check got evaluated
+    # before `configure` was generated.
+    #
+    # Remove this when the version is bumped
+    ./pkg-config-use-var.patch
+  ];
+
   nativeBuildInputs = [
     which pkgconfig perl
   ] ++ stdenv.lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [

pkgs/development/tools/misc/autogen/pkg-config-use-var.patch

@@ -0,0 +1,13 @@
+diff --git a/configure b/configure
+index c3f761d1c3f..14b101f67c1
+--- a/configure
++++ b/configure
+@@ -16683,7 +16683,7 @@ fi
+ 
+ 
+ 
+-  ag_gv=`gdir=\`pkg-config --cflags-only-I \
++  ag_gv=`gdir=\`${PKG_CONFIG} --cflags-only-I \
+   guile-${GUILE_EFFECTIVE_VERSION} | \
+   sed 's/\(^\| \)-I/\1/g'\`
+   for d in $gdir