[PUSHED] Avoid indexing std::vector past the end

[Ruslan Kabatsayev <b7 dot 10110111 at gmail dot com>]

The code here wants to find address of an element, and often this
element is one past the end of std::vector. Dereferencing that element
leads to undefined behavior, so it's better to simply use pointer
arithmetic instead of taking address of invalid dereference.

gdb/ChangeLog:

	* psymtab.c (recursively_search_psymtabs): Use pointer arithmetic
	instead of dereferencing std::vector past the end.
---
 gdb/ChangeLog |    5 +++++
 gdb/psymtab.c |    8 ++++----
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index edb3cd4..aaadf14 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2017-12-31  Ruslan Kabatsayev  <b7.10110111@gmail.com>
+
+	* psymtab.c (recursively_search_psymtabs): Use pointer arithmetic
+	instead of dereferencing std::vector past the end.
+
 2017-12-30  Simon Marchi  <simon.marchi@ericsson.com>
 
 	* common/diagnostics.h
diff --git a/gdb/psymtab.c b/gdb/psymtab.c
index c87ef25..1271e18 100644
--- a/gdb/psymtab.c
+++ b/gdb/psymtab.c
@@ -1337,21 +1337,21 @@ recursively_search_psymtabs
     }
 
   partial_symbol **gbound
-    = &objfile->global_psymbols[ps->globals_offset + ps->n_global_syms];
+    = objfile->global_psymbols.data () + ps->globals_offset + ps->n_global_syms;
   partial_symbol **sbound
-    = &objfile->static_psymbols[ps->statics_offset + ps->n_static_syms];
+    = objfile->static_psymbols.data () + ps->statics_offset + ps->n_static_syms;
   partial_symbol **bound = gbound;
 
   /* Go through all of the symbols stored in a partial
      symtab in one loop.  */
-  partial_symbol **psym = &objfile->global_psymbols[ps->globals_offset];
+  partial_symbol **psym = objfile->global_psymbols.data () + ps->globals_offset;
   while (keep_going)
     {
       if (psym >= bound)
 	{
 	  if (bound == gbound && ps->n_static_syms != 0)
 	    {
-	      psym = &objfile->static_psymbols[ps->statics_offset];
+	      psym = objfile->static_psymbols.data () + ps->statics_offset;
 	      bound = sbound;
 	    }
 	  else
-- 
1.7.10.2