JUCE updated to v5.4.2

ROLI / The JUCE Team have updated JUCE to v5.4.2.

Changes:

• Restructed the low-level Android native code.
• Added an ADSR envelope class.
• AudioProcessorValueTreeState performance improvements.
• Improved Xcode 10 support.
• Improved VST3 hosting.
• Windows hiDPI scaling enhancements.