Can't static link vectorscan into another shared library on Mac OS without exporting vectorscan symbols

[jeffplaisance]

I am using vectorscan in a shared library that is intended to be used with the jvm through jni. For various java-related reasons, the shared library is bundled in a jar file for distribution. Bundling multiple shared libraries into the jar and having one load the others is tricky and annoying, so I prefer to static link the dependencies of the library directly into the shared object file, so that it works standalone. For this to work correctly, it is important that I can control which symbols the library exports, as I don't want it to export any symbols from its dependencies, as they may potentially conflict with other versions of the same dependency that are also loaded by the same process. On gcc/linux I can use -Wl,--exclude-libs,ALL in the linker options to do this, but that doesn't work in clang/mac. To fix this, I am proposing the addition of #ifndef HS_PUBLIC_API ... #endif around the #define for HS_PUBLIC_API so that I can define it to be empty from cmake and avoid exporting the symbols.

[jeffplaisance]

i opened a pull request: #164