Add osmo_isqrt32() to compute 32bit integer square root

Change-Id: I2b96db6e037e72e92317fec874877e473a1cf909
diff --git a/tests/utils/utils_test.ok b/tests/utils/utils_test.ok
index 5bc3896..ea9216f 100644
--- a/tests/utils/utils_test.ok
+++ b/tests/utils/utils_test.ok
@@ -137,3 +137,5 @@
 '<buf-too-small>'
 - NULL string becomes a "NULL" literal:
 'NULL'
+
+Testing integer square-root