Fix for bug #5136(Geometry object corrupted after the query)

sql/item_geofunc.cc:
  We should force geometry's charset to be BINARY

sql/item_geofunc.cc

@@ -44,6 +44,7 @@ String *Item_func_geometry_from_text::val_str(String *str)
   if ((arg_count == 2) && !args[1]->null_value)
     srid= (uint32)args[1]->val_int();
 
+  str->set_charset(&my_charset_bin);
   if (str->reserve(SRID_SIZE, 512))
     return 0;
   str->length(0);
@@ -71,6 +72,7 @@ String *Item_func_geometry_from_wkb::val_str(String *str)
   if ((arg_count == 2) && !args[1]->null_value)
     srid= (uint32)args[1]->val_int();
 
+  str->set_charset(&my_charset_bin);
   if (str->reserve(SRID_SIZE, 512))
     return 0;
   str->length(0);
@@ -180,6 +182,7 @@ String *Item_func_envelope::val_str(String *str)
     return 0;
   
   srid= uint4korr(swkb->ptr());
+  str->set_charset(&my_charset_bin);
   str->length(0);
   if (str->reserve(SRID_SIZE, 512))
     return 0;
@@ -202,6 +205,7 @@ String *Item_func_centroid::val_str(String *str)
 					 swkb->length() - SRID_SIZE))))
     return 0;
 
+  str->set_charset(&my_charset_bin);
   if (str->reserve(SRID_SIZE, 512))
     return 0;
   str->length(0);
@@ -232,6 +236,7 @@ String *Item_func_spatial_decomp::val_str(String *str)
     return 0;
 
   srid= uint4korr(swkb->ptr());
+  str->set_charset(&my_charset_bin);
   if (str->reserve(SRID_SIZE, 512))
     goto err;
   str->length(0);
@@ -279,6 +284,7 @@ String *Item_func_spatial_decomp_n::val_str(String *str)
 					  swkb->length() - SRID_SIZE)))))
     return 0;
 
+  str->set_charset(&my_charset_bin);
   if (str->reserve(SRID_SIZE, 512))
     goto err;
   srid= uint4korr(swkb->ptr());
@@ -333,6 +339,7 @@ String *Item_func_point::val_str(String *str)
 		    str->realloc(1 + 4 + SIZEOF_STORED_DOUBLE*2))))
     return 0;
 
+  str->set_charset(&my_charset_bin);
   str->length(0);
   str->q_append((char)Geometry::wkb_ndr);
   str->q_append((uint32)Geometry::wkb_point);
@@ -358,6 +365,7 @@ String *Item_func_spatial_collection::val_str(String *str)
   String arg_value;
   uint i;
 
+  str->set_charset(&my_charset_bin);
   str->length(0);
   if (str->reserve(1 + 4 + 4, 512))
     goto err;