(Autoconf) Add X10 compiler support configuration

* Add ROSE_SUPPORT_X10 (m4 macro) to support these
  ROSE configuration options, including validation
  of the installation binaries and libraries:

      --with-x10
      --with-x10-bin
      --with-x10-lib

* Add ROSE_SUPPORT_X10_FRONTEND (m4 macro) to
  determine if the ROSE X10 Frontend is requested,
  and if the required X10 installation is available.

  TO-DO: Add x10 option to support-languages.m4, for
         --enable-languages=<languages>.

* House keeping for support-languages.m4.

Conflicts:

	config/support-x10.m4
(X10) Add initial .x10 file support
(X10) Implement call to X10 frontend

* Add SgSourceFile::build_X10_AST
* Add SgProject::get_X10_only
* Add SgProject::set_X10_only
* Add x10_main for X10 frontend JNI
* Add -rose:x10
(X10) Add backend support

* Add ROSE_SUPPORT_X10_BACKEND (m4 macro)
* Add SgFile::[get,set]_sourceFileUsesX10FileExtension
* Add minimal skeletons for X10 unparser (Unparse_X10)
* Add SageInterface::is_X10_language
* Refactor various local code regions

Conflicts:

	src/backend/unparser/unparser.C
(X10) Clean slate for README file
(X10) Add initial test code

The `HelloWholeWorld.x10` test code is passed through
the testTranslator in order to test:

  * Recognition of .x10 file extension/type
  * Call to x10c polyglot frontend
  * Call to x10c as backend compiler

Note: `-rose:output` is used in the Automake test to
avoid overriding the original source file in the
source tree. In the future, we probably want to
implement a less destructive default, i.e. unparse the
file into the build tree (see the Java work for an
example).
(X10) (Autoconf) Test X10 backend compiler

* X10 compiler is tested simply by passing it the
  -version commandline option.
* X10 frontend should be enabled, otherwise a warning
  will be issued during $ROSE/configure.
(X10) (Autoconf) Validate and normalize CLI argument

* Allow --enable-frontend-x10=[yes, no, true, false, auto-enable].
  Note that 'auto-enable' is intended for the case where the user
  does not specify --[enable,disable]--frontend-x10.

* Set AM_CONDITIONAL to false when X10 frontend is disabled.
(X10) Build libroseX10.la unconditionally

* Use dummy_x10_main.cpp if X10 is not enabled.
* Re-implemented dummy_x10_main.cpp.
(X10) Add if-branch to handle binary file condition

Jenkins failed `$ROSE/tests/roseTests/binaryTests` due
to a new assertion I added to make the code for building
the backend compiler commandline more robust.