Update 06-Considering_Portability.md

Author: lefticus

06-Considering_Portability.md

@@ -5,3 +5,7 @@
 Most portability issues that generate warnings are because we are not careful about our types. Standard library and arrays are indexed with `size_t`. Standard container sizes are reported in `size_t`. If you get the handling of `size_t` wrong, you can create subtle lurking 64-bit issues that arise only after you start to overflow the indexing of 32-bit integers. char vs unsigned char.
 
 http://www.viva64.com/en/a/0010/
+
+## Other Concerns
+
+Most of the other concerns in this document ultimately come back to portability issues. [Avoid statics](07-Considering_Threadability.md#statics) is particularly of note.