expose the python home in sys

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/PythonLanguage.java

@@ -325,6 +325,10 @@ protected Object findMetaObject(PythonContext context, Object value) {
         return null;
     }
 
+    public String getHome() {
+        return getLanguageHome();
+    }
+
     public static PythonLanguage getCurrent() {
         return getCurrentLanguage(PythonLanguage.class);
     }

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/SysModuleBuiltins.java

@@ -168,6 +168,7 @@ public void initialize(PythonCore core) {
                         PythonOptions.getFlag(core.getContext(), PythonOptions.QuietFlag), // quiet
                         PythonOptions.getFlag(core.getContext(), PythonOptions.VerboseFlag), // verbose
         }));
+        builtinConstants.put("graal_python_home", core.getContext().getLanguage().getHome());
         builtinConstants.put("graal_python_core_home", PythonOptions.getOption(core.getContext(), PythonOptions.CoreHome));
         builtinConstants.put("graal_python_stdlib_home", PythonOptions.getOption(core.getContext(), PythonOptions.StdLibHome));
         builtinConstants.put("graal_python_opaque_filesystem", PythonOptions.getOption(core.getContext(), PythonOptions.OpaqueFilesystem));