build: Fixes for gcc 5 compilation

build: Fixes for gcc 5 compilation

These are fixes for compilation under gcc 5.0...

chan_sip.c:    In parse_request needed to make 'lim' unsigned.
inline_api.h:  Needed to add a check for '__GNUC_STDC_INLINE__' to detect C99
               inline semantics (same as clang).
ccss.c:        In ast_cc_set_parm, needed to fix weird comparison.
dsp.c:         Needed to work around a possible compiler bug.  It was throwing
               an array-bounds error but neither
               sgriepentrog, rmudgett nor I could figure out why.
manager.c:     In action_atxfer, needed to correct an array allocation.

This patch will go to 11, 13, trunk.

Review: https://reviewboard.asterisk.org/r/4581/
Reported-by: Jeffrey Ollie
Tested-by: George Joseph
ASTERISK-24932 #close

Change-Id: I967d296cdf2c7834a2bdffd401b077a8a968d09b