For Travis CI - tweak the iOS universal binary build rule threshold.

Reduce the checkpoint from 20 minutes to 15 minutes. Also add logic to output the elasped time to aid future tweaking.

Rakefile

@@ -165,7 +165,11 @@ task :ci_package_upload do
   # Make the package
   if ENV['IOS']
     # Skip Mach-O universal binary build if Travis-CI VM took too long to get here, as otherwise overall build time may exceed 50 minutes time limit
-    if !ENV['CI_START_TIME'] || (Time.now - Time.parse(ENV['CI_START_TIME'])) / 60 < 20 # minutes
+    if ENV['CI_START_TIME'] then
+      elapsed_time = (Time.now - Time.parse(ENV['CI_START_TIME'])) / 60
+      puts "\niOS checkpoint reached, elapsed time: #{elapsed_time}\n\n"
+    end
+    if !ENV['CI_START_TIME'] || elapsed_time < 15 # minutes
       # Build Mach-O universal binary consisting of iphoneos (universal ARM archs including 'arm64' if 64-bit is enabled) and iphonesimulator (i386 arch and also x86_64 arch if 64-bit is enabled)
       system 'echo Rebuild Urho3D library as Mach-O universal binary'
       xcode_build(0, "#{platform_prefix}Build/Urho3D.xcodeproj", 'Urho3D_universal') or abort 'Failed to build Mach-O universal binary'