libgccjit: add new version entry point

libgccjit: add new version entry point

gcc/jit/ChangeLog
2020-03-31  Andrea Corallo  <andrea.corallo@arm.com>
	    David Malcolm  <dmalcolm@redhat.com>

	* docs/topics/compatibility.rst (LIBGCCJIT_ABI_13): New ABI tag
	plus add version paragraph.
	* libgccjit++.h (namespace gccjit::version): Add new namespace.
	* libgccjit.c (gcc_jit_version_major, gcc_jit_version_minor)
	(gcc_jit_version_patchlevel): New functions.
	* libgccjit.h (LIBGCCJIT_HAVE_gcc_jit_version): New macro.
	(gcc_jit_version_major, gcc_jit_version_minor)
	(gcc_jit_version_patchlevel): New functions.
	* libgccjit.map (LIBGCCJIT_ABI_13) New ABI tag.

gcc/testsuite/ChangeLog
2020-03-31  Andrea Corallo  <andrea.corallo@arm.com>

	* jit.dg/test-version.c: New testcase.
	* jit.dg/all-non-failing-tests.h: Add test-version.c.