libarchive: add patch to fix .pc file

(cherry picked from commit 505530e3de)

pkgs/by-name/li/libarchive/fix-pkg-config-iconv.patch

@@ -0,0 +1,18 @@
+diff --git a/configure.ac b/configure.ac
+index 0fdfaf06a5..d08611848c 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -453,13 +453,8 @@
+   AC_CHECK_HEADERS([iconv.h],[],[],[#include <stdlib.h>])
+   if test "x$am_cv_func_iconv" = "xyes"; then
+     AC_CHECK_HEADERS([localcharset.h])
+-    am_save_LIBS="$LIBS"
+     LIBS="${LIBS} ${LIBICONV}"
+-    if test -n "$LIBICONV"; then
+-      LIBSREQUIRED="$LIBSREQUIRED${LIBSREQUIRED:+ }iconv"
+-    fi
+     AC_CHECK_FUNCS([locale_charset])
+-    LIBS="${am_save_LIBS}"
+     if test "x$ac_cv_func_locale_charset" != "xyes"; then
+       # If locale_charset() is not in libiconv, we have to find libcharset.
+       AC_CHECK_LIB(charset,locale_charset)

pkgs/by-name/li/libarchive/package.nix

@@ -40,6 +40,22 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-maV2+Whi4aDG1VLAYpOTxluO9I0zNiZ8fA3w7epGlDg=";
   };
 
+  patches = [
+    # The `.pc` file lists `iconv` in `Requires.private` when `-liconv`
+    # is required, even though common platforms in that situation like
+    # Darwin don’t ship a `.pc` file for their `libiconv`. This isn’t
+    # upstreamed as there are a handful of closed or regressed PRs
+    # trying to fix it already and it seems upstream added this to deal
+    # with some non‐portable MSYS2 thing or something.
+    #
+    # See:
+    #
+    # * <https://github.com/libarchive/libarchive/issues/1766>
+    # * <https://github.com/libarchive/libarchive/issues/1819>
+    # * <https://github.com/Homebrew/homebrew-core/blob/f8e9e8d4f30979dc99146b5877fce76be6d35124/Formula/lib/libarchive.rb#L48-L52>
+    ./fix-pkg-config-iconv.patch
+  ];
+
   outputs = [ "out" "lib" "dev" ];
 
   postPatch = let