[libc][NFC] Use ASSERT_FP_EQ to compare nan values in tests.

This change "fixes" one of the uses that was missed in
0524da67b448dcce6569fae0f54c10f208c2dc56.

GitOrigin-RevId: cc07d5251144e12cc089748ec66af0423ba57ad1
diff --git a/test/src/math/RemQuoTest.h b/test/src/math/RemQuoTest.h
index 66f2f09..1e00ee1 100644
--- a/test/src/math/RemQuoTest.h
+++ b/test/src/math/RemQuoTest.h
@@ -123,7 +123,7 @@
       // In normal range on x86 platforms, the long double implicit 1 bit can be
       // zero making the numbers NaN. Hence we test for them separately.
       if (isnan(x) || isnan(y)) {
-        ASSERT_NE(isnan(result.f), 0);
+        ASSERT_FP_EQ(result.f, nan);
         continue;
       }