Fix interp::m_name resource leak found by Coverity

This commit fixes a resource leak found by Coverity, where interp's
constructor allocated memory for m_name that interp's destructor did
not free.

gdb/ChangeLog:

	* interps.h (interp::m_name): Make private and mutable.
	* interps.c (interp::~interp): Free m_name.

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2018-10-11  Gary Benson <gbenson@redhat.com>
+
+	* interps.h (interp::m_name): Make private and mutable.
+	* interps.c (interp::~interp): Free m_name.
+
 2018-10-10  Sergio Durigan Junior  <sergiodj@redhat.com>
 	    Simon Marchi <simark@simark.ca>
 

gdb/interps.c

@@ -84,7 +84,9 @@ interp::interp (const char *name)
 }
 
 interp::~interp ()
-{}
+{
+  xfree (m_name);
+}
 
 /* An interpreter factory.  Maps an interpreter name to the factory
    function that instantiates an interpreter by that name.  */

gdb/interps.h

@@ -80,10 +80,12 @@ public:
   }
 
   /* This is the name in "-i=" and "set interpreter".  */
-  const char *m_name;
+private:
+  char *m_name;
 
   /* Interpreters are stored in a linked list, this is the next
      one...  */
+public:
   struct interp *next;
 
   /* Has the init method been run?  */