configure: Fix log2f misdetection on some systems

Bug report by Dirk Fieldhouse.

diff --git a/configure b/configure
index 07ba4490f4be6699549c8ac2f2745a0512ccea77..3cf63e09861c04fc38fc1bd5fa629b5090556a07 100755 (executable)
--- a/configure
+++ b/configure
@@ -1067,7 +1067,7 @@ if [ "$thread" = "posix" ]; then
 fi
 [ "$thread" != "no" ] && define HAVE_THREAD
 
-if cc_check 'math.h' '' 'log2f(2);' ; then
+if cc_check 'math.h' '' 'volatile float x = 2; return log2f(x);' ; then
     define HAVE_LOG2F
 fi