Do not write CFI and symbols for deduplicate methods.

There is no need to have multiple symbols for a given address
since libunwind still has to pick only one to print.
Likewise, there is no need to duplicate the CFI.

There is fair number of duplicate methods in the boot image,
so this saves over 20% from those debug sections.

Change-Id: Ib4390150257d009a6303b084076750ce56afed60