Guile: add value-{rvalue-,}reference-value

The Guile API doesn't currently have an equivalent to the Python API's
Value.reference_value() or Value.rvalue_reference_value(). This commit
adds a procedure with equivalent semantics to the Guile API.

gdb/ChangeLog:

	* NEWS (Guile API): Note the addition of new procedures.
	* guile/scm-value.c (gdbscm_reference_value): Add helper function
	for reference value creation.
	(gdbscm_value_reference_value): Add implementation of
	value-reference-value procedure.
	(gdbscm_value_rvalue_reference_value): Add implementation of
	value-rvalue-reference-value procedure.
	(value_functions): Add value-reference-value procedure.  Add
	value-rvalue-reference-value procedure.

gdb/doc/ChangeLog:

	* guile.texi (Values From Inferior In Guile): Add documentation
	for value-reference-value.  Add documentation for
	value-rvalue-reference-value.

gdb/testsuite/ChangeLog:

	* gdb.guile/scm-value.exp (test_value_in_inferior): Add test for
	value-reference-value.  Add test for value-rvalue-reference-value.

1 files changed, 3 insertions, 0 deletions

diff --git a/gdb/NEWS b/gdb/NEWS
index 250f791..f7844e5 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -207,6 +207,9 @@ QMemTags
      value-referenced-value procedure now handles rvalue reference
      values.
 
+  ** New procedures for obtaining reference values:
+     value-reference-value and value-rvalue-reference-value.
+
 *** Changes in GDB 10
 
 * There are new feature names for ARC targets: "org.gnu.gdb.arc.core"