Define JNIEXPORT as visibility default with GCC?

[David DeHaven]

> This seems like an obvious improvement.
> There are already bunches of places in the jdk sources that do things like:
> 
> ./hotspot/src/cpu/x86/vm/jni_x86.h
> #if defined(SOLARIS) || defined(LINUX) || defined(_ALLBSD_SOURCE)
> 
> #if defined(__GNUC__) && (__GNUC__ > 4) || (__GNUC__ == 4) &&
> (__GNUC_MINOR__ > 2)
>  #define JNIEXPORT     __attribute__((visibility("default")))
>  #define JNIIMPORT     __attribute__((visibility("default")))
> #else
>  #define JNIEXPORT
>  #define JNIIMPORT
> #endif

That version check didn't work for me running on Mac OS X (using llvm-gcc 4.2). If that's what hotspot is using then they may not be getting the desired effect. The problem is __GNUC_MINOR__ is 2, so it needs to be changed to >= 2.

Gnu recommends just using "#if __GNUC__ >= 4", and everything I've read about it says it's 4.0 and later, so I don't understand why the minor version check is even in there.

-DrD-