8242490: Upgrade to gcc 9.2 on Linux

Reviewed-by: arapte, jvos

Author: kevinrushforth

build.properties

@@ -88,7 +88,7 @@ jfx.gradle.version=6.3
 jfx.gradle.version.min=5.3
 
 # Toolchains
-jfx.build.linux.gcc.version=gcc8.3.0-OL6.4+1.0
+jfx.build.linux.gcc.version=gcc9.2.0-OL6.4+1.0
 jfx.build.windows.msvc.version=VS2017-15.9.16+1.0
 jfx.build.macosx.xcode.version=Xcode10.1-MacOSX10.14+1.0