Darwin: fix bad loop incrementation

When reading symbols from the vector of oso files on Mac OS X
Darwin, a previous commit introduce a change in the loop and add
an increment at each loop iteration whereas this incrementation is
not needed since the increment or set of the loop control variable
is already done in the loop.

gdb/ChangeLog:

	* machoread.c (macho_symfile_read_all_oso): Remove uneeded
	incrementation.

Change-Id: I3a5a6deb4e9d834ee7d4217a62d90c2ffb7241bc

Author: Xavier Roirand

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2018-08-23  Xavier Roirand  <roirand@adacore.com>
+
+	* machoread.c (macho_symfile_read_all_oso): Remove uneeded
+	incrementation.
+
 2018-08-21  Alan Hayward  <alan.hayward@arm.com>
 
 	* arch/aarch64.h (aarch64_regnum): Update comment.

gdb/machoread.c

@@ -616,7 +616,7 @@ macho_symfile_read_all_oso (std::vector<oso_el> *oso_vector_ptr,
   std::sort (oso_vector_ptr->begin (), oso_vector_ptr->end (),
 	     oso_el_compare_name);
 
-  for (ix = 0; ix < oso_vector_ptr->size (); ++ix)
+  for (ix = 0; ix < oso_vector_ptr->size ();)
     {
       int pfx_len;