8156121: "Fail forward" fails for GTK3 if no GTK2 availableReviewed-by: prr
8156020: 8145547 breaks AIX and and uses RTLD_NOLOAD incorrectlyReviewed-by: prr, serb
8145547: [AWT/Swing] Conditional support for GTK 3 on LinuxReviewed-by: prr, alexsch