windows: Fix GC

[dragmz]

Fixes garbage collection on Windows by removing calls to SetGCPercent and replacing the GC stop with a native buffer allocation (LocalAlloc / LocalFree) for fixedInfoWithOverlay.

The previously used code didn't work well on Windows, causing the GC to stop from collecting. The SetGCPercent(pct) didn't restore the GC.

A minimal program that can be used to reproduce the issue with SetGCPercent on Windows:

package main

import "runtime/debug"

func test() {
	pct := debug.SetGCPercent(-1)
	defer debug.SetGCPercent(pct)

	var r [][]byte
	for i := 0; i < 10; i++ {
		r = append(r, make([]byte, 1024))
	}
}

func main() {
	for {
		test()
	}
}

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #5745 (8a1eae1) into master (ea20873) will increase coverage by 0.00%.
Report is 1 commits behind head on master.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #5745   +/-   ##
=======================================
  Coverage   55.57%   55.57%           
=======================================
  Files         476      476           
  Lines       66857    66857           
=======================================
+ Hits        37156    37157    +1     
+ Misses      27177    27175    -2     
- Partials     2524     2525    +1     

see 7 files with indirect coverage changes

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