gdb: make the target_sections table private within program_space

Following on from earlier commits which made access to the
target_sections table more 'const', this commit makes the table
private within the program_space class and provides member functions
to access the table.

Ideally I would have liked for the new target_sections member
function (on program_space) to return a 'const' reference to the table
within the program_space.  Unfortunately, there are two places in
solib-*.c, where code outside of the program_space class modifies the
target_sections table, and so to support this we need to return a
non-const reference.

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* exec.c (exec_target::close): Call new clear_target_sections
	function.
	(program_space::add_target_sections): Update name of member
	variable.
	(program_space::foreach_target_section): New function.
	(program_space::add_target_sections): Update name of member
	variable.
	(program_space::remove_target_sections): Likewise.
	(exec_one_fork): Use new target_sections member function.
	(exec_target::get_section_table): Likewise.
	(exec_target::files_info): Likewise.
	(set_section_command): Use new foreach_target_section member
	function.
	(exec_set_section_address): Likewise.
	(exec_target::has_memory): Use new target_sections member
	function.
	* progspace.h (program_space::clear_target_sections): New member
	function.
	(program_space::target_sections): Rename member variable to
	m_target_sections, replace with a new member function.
	(program_space::foreach_target_section): Declare new member
	function.
	(program_space::m_target_sections): New member variable.
	* solib-dsbt.c (scan_dyntag): Use new member function.
	* solib-svr4.c (scan_dyntag): Likewise.

1 files changed, 17 insertions, 4 deletions

diff --git a/gdb/progspace.h b/gdb/progspace.h
index 6ac8932..7906847 100644
--- a/gdb/progspace.h
+++ b/gdb/progspace.h
@@ -309,6 +309,18 @@ struct program_space
      sections.  They are given OBJFILE as the "owner".  */
   void add_target_sections (struct objfile *objfile);
 
+  /* Clear all target sections from M_TARGET_SECTIONS table.  */
+  void clear_target_sections ()
+  {
+    m_target_sections.clear ();
+  }
+
+  /* Return a reference to the M_TARGET_SECTIONS table.  */
+  target_section_table &target_sections ()
+  {
+    return m_target_sections;
+  }
+
   /* Unique ID number.  */
   int num = 0;
 
@@ -359,10 +371,6 @@ struct program_space
   /* All known objfiles are kept in a linked list.  */
   std::list<std::shared_ptr<objfile>> objfiles_list;
 
-  /* The set of target sections matching the sections mapped into
-     this program space.  Managed by both exec_ops and solib.c.  */
-  target_section_table target_sections;
-
   /* List of shared objects mapped into this space.  Managed by
      solib.c.  */
   struct so_list *so_list = NULL;
@@ -380,6 +388,11 @@ struct program_space
 
   /* Per pspace data-pointers required by other GDB modules.  */
   REGISTRY_FIELDS {};
+
+private:
+  /* The set of target sections matching the sections mapped into
+     this program space.  Managed by both exec_ops and solib.c.  */
+  target_section_table m_target_sections;
 };
 
 /* An address space.  It is used for comparing if