[JDK11] Configure scripts & code changes for RISC-V 64bit

[ChengJin01]

The issue is opened to include all the changes in JDK11 for eclipse-openj9/openj9#5058 to enable RISCV 64 bit as follows:
#219 , #220, #297

FYI: @keithc-ca, @pshipton , @DanHeidinga

[ChengJin01]

Jan Vrany (the external contributor on OMR/JIT) suggested me to double-check whether it is feasible to only do cross-compilation by mounting the Fedora_Linux OS image to the local system (used for --sysroot / previously pointed to the sysroot path in the cross-toolchain). Given that there are only a small piece of X11 related code changes and no changes on DDR (issue with the libdwarf library), I will first try to remove the changes on X11 to see how it goes. If everything goes fine, some of changes here will be updated/removed soon for the latest results.

[ChengJin01]

Already solved the compilation issue with X11 with --sysroot pointed to the mounted Fedora OS image and the created JDK works good in Fedora/QEMU. Now get started to check whether it is feasible to enable DDR (specifically get the cross-compiler to locate the sysroot path of dwarf related headers/libraries). Will remove all unnecessary changes with X11 soon.