[PATCH] Fix unitialized memory access in svn_canonicalize_path()

svn_path_canonicalize() will try to access a single byte before its
allocated buffer if the path specified is "". The attached patch fixes
this. I've confirmed the error and the fix with valgrind.

[[[
 * subversion/libsvn_subr/path.c (svn_canonicalize_path): Avoid
   accessing unitialized memory when path is "".
]]]

Cheers,

Jelmer