Don't use void pointer for arithmetic

Address Solaris warning: pointer to void or function used in arithmetic
(reported by Douglas Carmichael)

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
[test] Address Solaris warnings

Address the following Solaris warnings:

"test/test_sample_load_delta.c", line 8: warning: initializer does not fit
	or is out of range: -7
"test/test_sample_load_signal.c", line 8: warning: initializer does not fit
	or is out of range: -7
"test/test_sample_load_endian.c", line 8: warning: initializer does not fit
	or is out of range: -7

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Update changelog

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>