RISC-V: add build spec for native builds

This commit adds a RISC-V native build spec for CI testing. This is
intended to run on Eclipse CBI [1].

[1]: https://github.com/eclipse-cbi/cbi/wiki#whats-provided

buildenv/jenkins/omrbuild.groovy

@@ -180,6 +180,32 @@ SPECS = [
         'testArgs' : '',
         'junitPublish' : true
     ],
+    'linux_riscv64' : [
+        'alias': 'riscv',
+        'label' : 'hw.arch.riscv64',
+        'reference' : defaultReference,
+        'environment' : [
+            'PATH+CCACHE=/usr/lib/ccache/',
+            /*
+             * As of now, native RISC-V build agents are running as a Docker containers
+             * so we need to set OMR_RUNNING_IN_DOCKER even though the build itself does not
+             * use Docker. Otherwise sysinfo_is_running_in_container would fail.
+             */
+            'OMR_RUNNING_IN_DOCKER=1'
+        ],
+        'ccache' : false,
+        'buildSystem' : 'cmake',
+        'builds' : [
+            [
+                'buildDir' : cmakeBuildDir,
+                'configureArgs' : '-Wdev -C../cmake/caches/Travis.cmake',
+                'compile' : defaultCompile
+            ]
+        ],
+        'test' : true,
+        'testArgs' : '',
+        'junitPublish' : true
+    ],
     'linux_x86' : [
         'alias': 'x32linux',
         'label' : 'compile:xlinux',