Build failure on arm64 and mips64el

[matteobin]

The issue reported by @MikeWang000000 in #232 is causing a build failure on Debian arm64 and mips64el repository: https://buildd.debian.org/status/fetch.php?pkg=spek&arch=arm64&ver=0.8.5%2Bdfsg-1&stamp=1674401278&raw=0 https://buildd.debian.org/status/fetch.php?pkg=spek&arch=mips64el&ver=0.8.5%2Bdfsg-1&stamp=1674401012&raw=0

I'm going to use Mike's patch to momentarily fix this issue.

--- a/tests/test-fft.cc
+++ b/tests/test-fft.cc
@@ -62,7 +62,7 @@ static void test_sine()
                 if (i == k) {
                     continue;
                 }
-                if (plan->get_output(i) > -150.0f) {
+                if (plan->get_output(i) > -149.0f) {
                     silence = false;
                     break;
                 }

[alexkay]

Merged, thank you guys!