Removed compiler warning - implicit declaration of a function

Removed compiler warning - implicit declaration of a function

-Needed to include #include <string.h> before using the string functions.
-Already submitted a similar change.
-Some of the files here, which were showing warning, were already fixed.
But, seems some other change has removed the #include <string.h>. So, I am resubmitting it.
-Remaining files - earlier string functions were not being used.

Change-Id: I8d1c98de81ee39308343f42034c414501e60d653