Don't build and link mbedtls on Windows/Mac

contrib/mbedtls/premake5.lua

@@ -16,4 +16,5 @@ project "mbedtls-lib"
 		"library/*.c"
 	}
 
-
+	filter { "system:windows or macosx" }
+		flags { "ExcludeFromBuild" }

premake5.lua

@@ -136,7 +136,7 @@
 		end
 		if not _OPTIONS["no-curl"] then
 			includedirs { "contrib/curl/include" }
-			links { "curl-lib", "mbedtls-lib" }
+			links { "curl-lib" }
 		end
 
 		files
@@ -169,6 +169,11 @@
 		filter "system:linux or hurd"
 			links       { "dl", "rt" }
 
+		filter { "system:not windows", "system:not macosx" }
+			if not _OPTIONS["no-curl"] then
+				links   { "mbedtls-lib" }
+			end
+
 		filter "system:macosx"
 			defines     { "LUA_USE_MACOSX" }
 			links       { "CoreServices.framework", "Foundation.framework", "Security.framework" }