exclude log2 usage which requires C99 support

diff --git a/ext/standard/config.m4 b/ext/standard/config.m4
index 67952163aab76618e05dce9f1332d49fcf37213b..7a5f0effa01997ab6a4e2c68351a6f77be4b7d4a 100644 (file)
--- a/ext/standard/config.m4
+++ b/ext/standard/config.m4
@@ -338,7 +338,9 @@ fi
 dnl
 dnl Check for available functions
 dnl
-AC_CHECK_FUNCS(getcwd getwd asinh acosh atanh log1p log2 hypot glob strfmon nice fpclass isinf isnan mempcpy strpncpy)
+dnl log2 could be used to improve the log function, however it requires C99. The check for log2 should be turned on,
+dnl as soon as we support C99.
+AC_CHECK_FUNCS(getcwd getwd asinh acosh atanh log1p hypot glob strfmon nice fpclass isinf isnan mempcpy strpncpy)
 AC_FUNC_FNMATCH        
 
 dnl