Refactor tone portamento code

Reorganize tone portamento data and make it separate from pitch slide
data, avoid multiplications to determine direction of portamento slide.

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Supress a few warnings when using Solaris Studio

Use pragmas to keep the Solaris Studio compiler quiet about empty
translation units and unreachable code in certain files.

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
[test] Improve module test and load tests

- check for decompression error in module test
- check for decompression error in module load
- check for read permission in module test

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

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