Darwin: Fix gdb compilation.

Due to changes introduced by
commit 4d01a485d29732b19743e8b138897f3509e071b0
('struct expression *' -> gdb::unique_xmalloc_ptr<expression>)
compilation is broken on Darwin.

../gdb/darwin-nat-info.c:733:8: error: assigning to 'struct expression *'
from incompatible type
'expression_up' (aka 'std::__1::unique_ptr<expression, gdb::xfree_deleter<expression> >')
expr = parse_expression (exp);

Beside compilation, memory leak was solved as 'make_clean_up' was not called in previous
version.

2016-12-16  Bernhard Heckel  <bernhard.heckel@intel.com>

gdb/Changelog:
        * darwin-nat-info.c (info_mach_region_command): Use expression_up.

Change-Id: I863128c4755877789ef0f479415b7709784b3e17
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 4431e74..30779c0 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -16,6 +16,10 @@
 	* aarch64-fuchsia-tdep.h: New file.
 	* configure.tgt: Add aarch64-*-fuchsia*.
 
+2016-12-16  Bernhard Heckel  <bernhard.heckel@intel.com>
+
+	* darwin-nat-info.c (info_mach_region_command): Use expression_up.
+
 2016-12-16  Doug Evans  <dje@google.com>
 
 	* objfile-flags.h (objfile_flag): Add comment.
diff --git a/gdb/darwin-nat-info.c b/gdb/darwin-nat-info.c
index 314d265..0262026 100644
--- a/gdb/darwin-nat-info.c
+++ b/gdb/darwin-nat-info.c
@@ -725,13 +725,12 @@
 static void
 info_mach_region_command (char *exp, int from_tty)
 {
-  struct expression *expr;
   struct value *val;
   mach_vm_address_t address;
   struct inferior *inf;
 
-  expr = parse_expression (exp);
-  val = evaluate_expression (expr);
+  expression_up expr = parse_expression (exp);
+  val = evaluate_expression (expr.get ());
   if (TYPE_CODE (value_type (val)) == TYPE_CODE_REF)
     {
       val = value_ind (val);