Add gcc check for -pthreads if -pthread check fails. bug #44504 Thanks to madams@janna.com (Mark G. Adams) for the patch.

configure.in

@@ -2015,6 +2015,26 @@ then
 		fi
 	fi
 	rm -f conftest*
+    AC_MSG_RESULT($ac_cv_have_dash_pthread)
+
+	dnl
+	dnl See if -pthreads is supported.
+	dnl
+    ac_cv_have_dash_pthreads=no
+    if test "$ac_cv_have_dash_pthread" = "no"; then
+	    AC_MSG_CHECKING(whether ${CC-cc} accepts -pthreads)
+    	echo 'int main() { return 0; }' | cat > conftest.c
+	    ${CC-cc} -pthreads -o conftest conftest.c > conftest.out 2>&1
+    	if test $? -eq 0; then
+	    	if test -z "`egrep -i '(unrecognize|unknown)' conftest.out | grep pthreads`" && test -z "`egrep -i '(error|incorrect)' conftest.out`" ; then
+			    ac_cv_have_dash_pthreads=yes
+			    CFLAGS="$CFLAGS -pthreads"
+			    CXXFLAGS="$CXXFLAGS -pthreads"
+		    fi
+	    fi
+	    rm -f conftest*
+    	AC_MSG_RESULT($ac_cv_have_dash_pthreads)
+    fi
 
 	case "$target" in
 	    *-*-freebsd*|*-*-openbsd*)
@@ -2053,7 +2073,6 @@ then
 			fi
 			;;
 	esac
-	AC_MSG_RESULT($ac_cv_have_dash_pthread)
 fi
 
 dnl