refs #100891 Drop use of GCC variable in favor of existing variable CC.

The CC default is set when 'configure' is run.  If someone wishes to override the toolchain
used they can set a new value, which will support cross compilation
scenarios.
Refs #100894  Fix some compilation warnings
Refs #100894 Fix statement not reached warnings in sync_diff.c
Refs #100894 Fix statement not reached warning in ccnr_internal_client.c
Refs #100894 Fix statement not reached warning in ccnr_store.c
Refs #100894 Fix assignment type mismatch in ccnr_proto.c
Refs #100894 Remove unreachable code from ccnr_internal_client.c
Refs #100894 Fix empty initializers in ccn_btree.c
Refs #100894 Oracle C type-checks the assignment in return(x=7,NULL) incorrectly.
Refs #100894 Fix set-but-not-used variables warnings.
Refs #100894 Fix set-but-not-used variable warning.
Refs #100894 Fix set-but-not-used variable warning.
Refs #100894 Fix set-but-not-used warning in SyncTest.c
Refs #100894 Fix set-but-not-used warning in SyncActions.c
Refs #100894 Fix set-but-not-used warning in sync_diff.c
Refs #100894 Fix set-but-not-used warning in sync_diff.c
Merge branch '100894-warnings' of sylvester.parc.xerox.com:/project/ccnx/external into 100894-warnings
Refs #100894 fix editing mistake.
Refs #100894 Fix set-but-not-used warning in ccncatchunks2.c
Refs #100892 Fix warning/bug for wrong size initializing stats counters