Don't skip forking for an external command if any traps are active.

Example:
  sh -c '(trap "echo trapped" EXIT; sleep 3)'
now correctly prints "trapped".

With this check, it is no longer necessary to check for -T
explicitly in that case.

diff --git a/eval.c b/eval.c
--- a/eval.c
+++ b/eval.c
@@ -730,7 +730,7 @@ evalcommand(union node *cmd, int flags, 
 	/* Fork off a child process if necessary. */
 	if (cmd->ncmd.backgnd
 	 || (cmdentry.cmdtype == CMDNORMAL
-	    && ((flags & EV_EXIT) == 0 || Tflag))
+	    && ((flags & EV_EXIT) == 0 || have_traps()))
 	 || ((flags & EV_BACKCMD) != 0
 	    && (cmdentry.cmdtype != CMDBUILTIN
 		 || cmdentry.u.index == CDCMD
diff --git a/trap.c b/trap.c
--- a/trap.c
+++ b/trap.c
@@ -222,6 +222,21 @@ clear_traps(void)
 
 
 /*
+ * Check if we have any traps enabled.
+ */
+int
+have_traps(void)
+{
+	char *volatile *tp;
+
+	for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) {
+		if (*tp && **tp)	/* trap not NULL or SIG_IGN */
+			return 1;
+	}
+	return 0;
+}
+
+/*
  * Set the signal handler for the specified signal.  The routine figures
  * out what it should be set to.
  */
diff --git a/trap.h b/trap.h
--- a/trap.h
+++ b/trap.h
@@ -39,6 +39,7 @@ extern volatile sig_atomic_t gotwinch;
 
 int trapcmd(int, char **);
 void clear_traps(void);
+int have_traps(void);
 void setsignal(int);
 void ignoresig(int);
 void onsig(int);