Description of problem:
the CHANGELOG_GET_ENCODING macro uses the elen variable within the do/while statement. This is a value outside of the macro (xlators/features/changelog/lib/gf_changelog_process.c:gf_changelog_decode() ).
The macro should use the enc_len macro agtument. 

As written, this macro can only be used in functions where elen is in scope. 

Version-Release number of selected component (if applicable):
3.5

How reproducible:
All

Steps to Reproduce:
1. Review line 55 of https://github.com/gluster/glusterfs/blame/master/xlators/features/changelog/src/changelog-misc.h#L55
2.
3.

Actual results:
elen = strlen (buffer) ;

Expected results:
enc_len = strlen (buffer) ;

Additional info: