Fix buffer overflows in shortcut and workspace name handling

The handling of user defined shortcuts was not checking the length
of the shortcut before copying it to a fixed-length temporary buffer,

char buf[128];

     strcpy(buf, shortcutDefinition);

and strcpy() is well known for not checking if overflows will occur.

In particular, wmaker was crashing here if a big 'shortcut' was defined
either through WPrefs or by directly editing the configuration files.

This is now avoided by using strncpy() instead.

And this patch also fixes a similar buffer overflow for big workspace
names too.

Furthermore, use MAX_SHORTCUT_LENGTH instead of raw number and define
it to be 32 instead of 128.

src/rootmenu.c

@@ -55,7 +55,7 @@
 
 #include <WINGs/WUtil.h>
 
-
+#define MAX_SHORTCUT_LENGTH 32
 
 extern char *Locale;
 
@@ -513,11 +513,11 @@ addShortcut(char *file, char *shortcutDefinition, WMenu *menu,
     Shortcut *ptr;
     KeySym ksym;
     char *k;
-    char buf[128], *b;
+    char buf[MAX_SHORTCUT_LENGTH], *b;
 
     ptr = wmalloc(sizeof(Shortcut));
 
-    strcpy(buf, shortcutDefinition);
+    strncpy(buf, shortcutDefinition, MAX_SHORTCUT_LENGTH);
     b = (char*)buf;
 
     /* get modifiers */