MFC 296416:

Signal handling within tcsh vfork code path will conflict with some system
libraries (such as libthr) which maintain their own signal state. This
change adds the tcsh SAVESIGVEC option to save and restore the sigvecs for
the signals the child modifies before it execs.

Reviewed by:	kib, rwatson
Reported by:	kib
Approved by:	re

bin/csh/config_p.h

@@ -80,6 +80,7 @@
 /****************** local defines *********************/
 
 #if defined(__FreeBSD__)
+#define	SAVESIGVEC
 #define NLS_BUGS
 #define BSD_STYLE_COLORLS
 /* Use LC_MESSAGES locale category to open the message catalog */