improve libjpeg

packages/l/libjpeg/xmake.lua

@@ -15,7 +15,7 @@ package("libjpeg")
         os.cp("libjpeg.lib", package:installdir("lib"))
     end)
 
-    on_install(function (package)
+    on_install("linux", "macosx", "iphoneos", "android", function (package)
         import("package.tools.autoconf").install(package, {"--enable-shared=no"})
     end)
 

packages/z/zlib/xmake.lua

@@ -19,7 +19,7 @@ package("zlib")
         os.cp("zlib.lib", package:installdir("lib"))
         os.cp("*.h", package:installdir("include"))
     end)
-
+ 
     on_install("iphoneos", "android", "mingw", function (package)
         import("package.tools.autoconf").configure(package, {host = "", "--static"})
         io.gsub("Makefile", "\nAR=.-\n",      "\nAR=" .. (package:build_getenv("ar") or "") .. "\n")