PPE: add unused attribute to a few functions

Caught by Clang 3.4.
update infra

* submodules/infra 6898254...3913825 (14):
  > Merge into master from pull request #25: AIM: add wrappers for __attribute__ (https://github.com/floodlight/infra/pull/25)
  > Add aim_bitmap 512.
  > Merge into master from pull request #24: Always update the modulemake file by default. (https://github.com/floodlight/infra/pull/24)
  > Support flag maps. - Enumerations that are defined as flag bits can be registered as a flag map datatype. - Flagmap datatypes are displayed in the following format: 0x%.8x [f0,f1,f2...fn]
  > Merge into master from pull request #23: Support to check if two aim bitmaps have any intersecting bits. (https://github.com/floodlight/infra/pull/23)
  > Merge into master from pull request #21: modify log time format (https://github.com/floodlight/infra/pull/21)
  > Merge into master from pull request #22: Updates for use in shared libraries.  (https://github.com/floodlight/infra/pull/22)
  > Merge into master from pull request #20: AIM: add early check for log level (https://github.com/floodlight/infra/pull/20)
  > Merge into master from pull request #19: Allow customization of the aim_main() function name. (https://github.com/floodlight/infra/pull/19)
  > Support optional AIM library constructor/destructor. - Allows module initialization in shared library builds. - Support for this feature is GCC-specific.
  > The LIBRARY_TARGETS_LAST list must be moved to the end every time a new library is added.
  > Support the LIBRARY_LAST attribute. - Libraries that indicate the LAST attribute will always be kept at the end of the global LIBRARY_TARGETS list.   The ordering between LAST libraries is arbitrary.
  > Merge into master from pull request #18: AIM: fix aim_pvs_buffer_iterate after reset (https://github.com/floodlight/infra/pull/18)
  > Merge into master from pull request #17: Support string format and duplication using AIM datatype formatting. (https://github.com/floodlight/infra/pull/17)
Merge into master from pull request #31:
PPE: add unused attribute to a few functions (https://github.com/floodlight/bigcode/pull/31)