do not include math modules in the default -O3 optimization set

it's not clear that -O3 helps them, and gcc seems to have floating
point optimization bugs that introduce additional failures when -O3 is
used on some of these files.

configure

@@ -264,7 +264,7 @@ xno|x) printf "disabled\n" ; optimize=no ;;
 esac
 
 test "$optimize" = no || tryflag CFLAGS_AUTO -Os || tryflag CFLAGS_AUTO -O2
-test "$optimize" = yes && optimize="internal,malloc,math,string"
+test "$optimize" = yes && optimize="internal,malloc,string"
 
 if fnmatch 'no|size' "$optimize" ; then :
 else