Changes

Add GitLab CI .gitlab-ci.yml, build and test each commit on aarch64 and
x86-64 linux systems.

Bug 1295: Add linux-aarch64 GNU/Linux AArch64 support
make/build.xml: New target declare.linux.aarch64
               Update target declare.linux to depend on
declare.linux.aarch64 make/gluegen-cpp-tasks-base.xml: Fix aarch64
jre/lib/arm -> jre/lib/aarch64 
make/lib/gluegen-cpptasks-linux-aarch64.xml: Added 
make/scripts/make.gluegen.all.linux-aarch64.sh: Added
Tested on DragonBoard 410c running Linaro Debian Platform: LINUX /
Linux 4.4.8-linaro-lt-qcom (4.4.8), aarch64 (ARM64, EABI_AARCH64), 4
cores, littleEndian true MachineDataInfo: runtimeValidated true, 32Bit
false, primitive size / alignment:
 int8    1 / 1, int16   2 / 2
 int     4 / 4, long    8 / 8
 int32   4 / 4, int64   8 / 8
 float   4 / 4, double  8 / 8, ldouble 16 / 16
 pointer 8 / 8, page    4096 Platform: Java Version: 1.8.0_91
(1.8.0u91), VM: OpenJDK 64-Bit Server VM, Runtime: OpenJDK Runtime
Environment Platform: Java Vendor: Oracle Corporation,
http://java.oracle.com/, JavaSE: true, Java6: true, AWT enabled: true
Signed-off-by: Xerxes Ranby <xerxes@gudinna.com>

Bug 1295: Add linux-aarch64 GNU/Linux AArch64 crosscompile support
make/lib/gluegen-cpptasks-linux-aarch64.xml:
 Add missing -DisLinux=true required when crosscompiling
 Remove -marm -mfloat-abi=hard flags unrecognisable by aarch64
crosscompile toolchain
make/lib/toolchain/aarch64-linux-gnueabi/bin/*:
 Symlink to
/usr/local/x-tools/aarch64-unknown-linux-gnueabi/bin/aarch64-unknown-linux-gnueabi-*
make/scripts/make.gluegen.all.linux-aarch64-cross.sh:
 New crosscompile script
make/stub_includes/platform/glibc-compat-symbols.h:
 glibc 2.17 is the first glibc version that support aarch64
 however memcpy is not versioned for aarch64
 Disable versioning for linux glibc/aarch64
Signed-off-by: Xerxes Rånby <xerxes@gudinna.com>

HowToBuild: Refine and add Debian 9 (Stretch)

Factor out Cleaner access for general use (Cleaning up NIO
DirectBuffer)