memory-leak / corruption with large string assignments

[mdijkens]

Describe the bug
When (re)assigning a string variable with a large string (>1GB) after a few times program crashes

To Reproduce
Steps to reproduce the behavior:
c$=space$(1123123123)
c$=space$(1123123123)
c$=space$(1123123123)
c$=space$(1123123123)
c$=space$(1123123123)
c$=space$(1123123123)
c$=space$(1123123123)

Expected behavior
Program ends/continues normally

Screenshots
Program just aborts/killed

Desktop (please complete the following information):

• OS: Windows 10
• Version 3.14.1

Additional context
Ran into issue with c$=ReadFile$() reading multiple large files in a loop

[mdijkens]

See also https://qb64phoenix.com/forum/showthread.php?tid=3130

[mkilgore]

The underlying issue is already reported here: #278

But note that due to how the string buffer is handled you'll need almost twice the total memory for the strings you create (so if you want to make 32GB of strings, you need around 64GB of total memory). Really, to be able to handle that much data the qbs string logic needs to be significantly improved.