Detect FreeBSD sigaltstack bug with -pthread

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@4972 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

configure

@@ -957,11 +957,18 @@ else
   debugger=""
 fi
 
+
 # Determine if system stack overflows can be detected
 
 case "$arch,$model,$system" in
   i386,*,*)
-    if ./runtest -DTARGET_$arch -DSYS_$system stackov.c; then
+    case "$host" in              # Check for FreeBSD 4.5 bug
+      *-*-freebsd*|*-*-openbsd*) check_pthread=yes ;;
+      *)                         check_pthread=no ;;
+    esac
+    if ./runtest -DTARGET_$arch -DSYS_$system stackov.c \
+    && test $check_pthread = no || cclibs="-pthread $cclibs" \
+           ./runtest -DTARGET_$arch -DSYS_$system stackov.c; then
       echo "System stack overflow can be detected."
       echo "#define HAS_STACK_OVERFLOW_DETECTION" >> s.h
     else
@@ -970,7 +977,6 @@ case "$arch,$model,$system" in
   *)
       echo "Cannot detect system stack overflow.";;
 esac
-
 # Determine the target architecture for the "num" library
 
 case "$host" in