Add ext source for util-linux (#792)

* Add ext source for util-linux

* Make libxml2 work with system libiconv

Don't hard code installdir(). When using system libiconv, there isn't a
installdir.

packages/l/libxml2/xmake.lua

@@ -104,7 +104,16 @@ package("libxml2")
             table.insert(configs, "--enable-static=yes")
         end
         if package:config("iconv") then
-            table.insert(configs, "--with-iconv=" .. package:dep("libiconv"):installdir())
+            local iconvdir
+            local iconv = package:dep("libiconv"):fetch()
+            if iconv then
+                iconvdir = table.wrap(iconv.sysincludedirs or iconv.includedirs)[1]
+            end
+            if iconvdir then
+                table.insert(configs, "--with-iconv=" .. path.directory(iconvdir))
+            else
+                table.insert(configs, "--with-iconv")
+            end
         else
             table.insert(configs, "--without-iconv")
         end

packages/u/util-linux/xmake.lua

@@ -11,7 +11,9 @@ package("util-linux")
 
     add_patches("2.36.2", path.join(os.scriptdir(), "patches", "2.36.2", "includes.patch"), "7274762cac2810b5f0d17ecb5ac69c7069e7ff2b880df663b7072628df0867f3")
 
-    if not is_plat("macosx") then
+    if is_plat("macosx") then
+        add_extsources("brew::util-linux")
+    else
         add_deps("ncurses", "zlib")
     end
 
@@ -42,8 +44,6 @@ package("util-linux")
                          "--disable-silent-rules",
                          "--without-python",
                          "--without-systemd",
-                         "--enable-static=yes",
-                         "--enable-shared=no",
                          "--with-bashcompletiondir=" .. package:installdir("share/bash-completion")}
         table.insert(configs, "--enable-shared=" .. (package:config("shared") and "yes" or "no"))
         table.insert(configs, "--enable-static=" .. (package:config("shared") and "no" or "yes"))