Fix issue with atomic variables on ppc64le

[beorn7]

@dswarbrick could you try out if this PR fixes #1165 on ppc64le ?

[dswarbrick]

@beorn7 Sadly it still fails on ppc64le

--- FAIL: TestNativeHistogram (0.00s) --- FAIL: TestNativeHistogram/factor_4_results_in_schema_-1 (0.00s) panic: runtime error: integer divide by zero [recovered] panic: runtime error: integer divide by zero goroutine 3012 [running]: testing.tRunner.func1.2({0x414f60, 0x7f64f0}) /usr/lib/go-1.19/src/testing/testing.go:1396 +0x1fc testing.tRunner.func1() /usr/lib/go-1.19/src/testing/testing.go:1399 +0x364 panic({0x414f60, 0x7f64f0}) /usr/lib/go-1.19/src/runtime/panic.go:884 +0x240 github.com/prometheus/client_golang/prometheus.(*histogramCounts).observe(0xc00012d170, 0xc000054d18?, 0xb0750?, 0x0?) /home/dswarbrick/client_golang/prometheus/histogram.go:632 +0x324 github.com/prometheus/client_golang/prometheus.(*histogram).observe(0xc000189520, 0x3fe0000000000000, 0x10?) /home/dswarbrick/client_golang/prometheus/histogram.go:803 +0xa4 github.com/prometheus/client_golang/prometheus.(*histogram).Observe(0xc000189520, 0xa9bbfd65e?) /home/dswarbrick/client_golang/prometheus/histogram.go:703 +0x5c github.com/prometheus/client_golang/prometheus.TestNativeHistogram.func1(0xc000126b60) /home/dswarbrick/client_golang/prometheus/histogram_test.go:674 +0x370 testing.tRunner(0xc000126b60, 0xc0001288f0) /usr/lib/go-1.19/src/testing/testing.go:1446 +0x11c created by testing.(*T).Run /usr/lib/go-1.19/src/testing/testing.go:1493 +0x36c FAIL github.com/prometheus/client_golang/prometheus 15.567s 

[beorn7]

Too bad… that makes it more likely that we are indeed running into a compiler error here. However, your minimal examples to trigger the presumed compiler error do not work with my fix here. Mysterious…
Without a minimal example to trigger the bug, it will be hard to report to the Go developers.

@bwplotka @kakkoyun I think we should still merge this, even if it is only there to rule out the case that initialization might not be synchronized with atomic operations.

[bwplotka]

Thanks!