Fixed the operator error in ssw.c

1. Fixed a wrong operator in ssw.c
2. Made the C++ API return alignment result flag.

The segmentation fault is removed.

1. The segmentation fault is removed.
2. Apple M1 CPU is supported.
3. Used by Pillar.

old gcc support

1. This version's source codes support old gcc compiler.
2. It has a c function that modifies cigar to indicate mismatches.
3. The speed is slightly lower than the "stable" release.

stable

This is a stable version of SSW.

For this version, please set the gap open penalty larger than the gap extension penalty to guarantee correct results.