RFR(S) 8190737: use unicode version of the canonicalize() function to handle long path on windows

[Calvin Cheung]

bug: https://bugs.openjdk.java.net/browse/JDK-8190737
webrev: http://cr.openjdk.java.net/~ccheung/8190737/webrev.00/

Please review this change for handling long path specified in the 
-Xbootclasspath/a on windows.

Highlight of changes:
- canonicalize_md.c
    it makes use of the unicode version of canonicalize (wcanonicalize) 
if the original path is >= MAX_PATH.

- zip_util.c
    it uses the unicode version of CreateFile (CreateFileW) if the 
original path is >= MAX_PATH.

- io_util_md.c
    Since zip_util.c (libzip) calls the getPrefixed() function in 
canonicalize_md.c (libjava), the getPrefixed() function needs to be 
exported.

- java_md.h
    The JVM_MAXPATHLEN has been increased from _MAX_PATH to 1024. It is 
because the the current usage of the canonicalize() function from vm 
code is to preallocate the output buffer as follows:
            char* canonical_path = NEW_RESOURCE_ARRAY_IN_THREAD(thread, 
char, JVM_MAXPATHLEN);
            if (!get_canonical_path(path, canonical_path, 
JVM_MAXPATHLEN)) {
    Also the unix version of canonicalize() function has the following 
check:
            int
           canonicalize(char *original, char *resolved, int len)
           {
               if (len < PATH_MAX) {
               errno = EINVAL;
               return -1;
           }
   So dynamically allocating the output buffer requires more work 
beyond the scope of this change.

- LongBCP.java
    added a scenario to the test - a long path to a jar file in 
-Xbootclasspath/a.

Testing: tier-[1,2,3].

thanks,
Calvin