8201226: missing JNIEXPORT / JNICALL at some places in function declarations/implementations

Co-authored-by: Alexey Ivanov <alexey.ivanov@oracle.com>
Reviewed-by: ihse, mdoerr

src/jdk.pack/share/native/unpack200/main.cpp

@@ -59,7 +59,7 @@
 #include "unpack.h"
 
 
-JNIEXPORT int JNICALL
+JNIEXPORT int
 main(int argc, char **argv) {
     return unpacker::run(argc, argv);
 }