Init petattr in core, not in curses

My recent change to petattr caused a crash in curses when no
petattr was used in config file - because curses was setting
petattr to curses-specific value.  Init the setting in core
instead.

src/options.c

@@ -6813,6 +6813,7 @@ initoptions_init(void)
     iflags.wc_align_status = ALIGN_BOTTOM;
     /* used by tty and curses */
     iflags.wc2_statuslines = 2;
+    iflags.wc2_petattr = ATR_INVERSE;
     /* only used by curses */
     iflags.wc2_windowborders = 2; /* 'Auto' */