Currently, JNIEXPORT is defined as 'extern "C"' on Solaris and Linux in HotSpot,
on Windows it is defined as '__declspec(dllexport)'. On Solaris and Linux, it
will force C linkage, but on Windows it does not. As the result, some JVM
functions have C linkage on Solaris/Linux, but C++ linkage on Windows
(e.g. JVM_RegisterUnsafeMethods), that doesn't sound right.

We should redefine JNIEXPORT and follow the definition in JDK, that is,
empty on Solaris/Linux, '__decl(dllexport)' on Windows. JNIEXPORT only makes
a symbol public, it has nothing to do with a symbol's linkage type. All public
JVM functions should have C linkage, and they should be wrapped explicitly
inside 'extern "C" { ... }"

###@###.### 2004-08-20