Added missing curly brackets and fixed compiler warnings.
Disable SSL when compiling for AmigaOS for now.
Compile regexp dependency when AMIGA is defined.

Before it was compiled when CMake was actually run on AmigaOS.
Add -fPIC only if BUILD_SHARED_LIBS is ON
Ignore build-amiga
Merge pull request #1218 from sba1/amiga.2

Libgit2 for AmigaOS4