Synchronize function comment in MdePkg\Library\BaseLib.h with the instance of this functions.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@6718 6f19259b-4bc3-4df7-8a09-765794883524

MdePkg/Library/BaseLib/DivS64x64Remainder.c

@@ -26,6 +26,10 @@
   NULL, then the 64-bit signed remainder is returned in Remainder. This
   function returns the 64-bit signed quotient.
 
+  It is the caller<65><72>s responsibility to not call this function with a Divisor of 0.
+  If Divisor is 0, then the quotient and remainder should be assumed to be 
+  the largest negative integer.
+
   If Divisor is 0, then ASSERT().
 
   @param  Dividend  A 64-bit signed value.