Fix access to files with long file names on win32/win64
Long path were already handled with a prefix '\\?\' thanks to ALLOC_WIN32_PATH macro defined in platforms/win32/plugins/FilePlugin/sqWin32File.h
Unfortunately, when concatenating a file path shorter than MAX_PATH with a file name making the total longer than MAX_PATH,
using the macro REALLOC_WIN32_PATH, there were no '\\?\' prepended, and the file access did fail...
This commit does fix the REALLOC_WIN32_PATH to handle the case when path become longer than limit after growth.