arm-mmp2: move "third" word to lcd.fth

It is the only user and having to define it before loading lcd.fth sort
of sucks.
diff --git a/src/app/arm-mmp2/lcd.fth b/src/app/arm-mmp2/lcd.fth
index 184a759..202c29b 100644
--- a/src/app/arm-mmp2/lcd.fth
+++ b/src/app/arm-mmp2/lcd.fth
@@ -91,6 +91,8 @@
    0 h# 138 lcd!   \ Color key V
 ;
 
+: third  ( a b c -- a b c a )  2 pick  ;
+
 : centered  ( w h -- )
    hdisp third - 2/               ( w h x )    \ X centering offset
    vdisp third - 2/               ( w h x y )  \ Y centering offset
diff --git a/src/app/arm-mmp3-thunderstone/basics.fth b/src/app/arm-mmp3-thunderstone/basics.fth
index ff4c3d9..f07b0c4 100644
--- a/src/app/arm-mmp3-thunderstone/basics.fth
+++ b/src/app/arm-mmp3-thunderstone/basics.fth
@@ -10,7 +10,6 @@
 fl ../arm-xo-1.75/addrs.fth
 
 : wljoin  ( w w -- l )  d# 16 lshift or  ;
-: third  ( a b c -- a b c a )  2 pick  ;
 
 \ [ifdef] INCLUDE-DISPLAY
 fl ../arm-mmp2/lcd.fth
diff --git a/src/app/arm-xo-1.75/olpcbasics.fth b/src/app/arm-xo-1.75/olpcbasics.fth
index 40e39b8..ef86b95 100644
--- a/src/app/arm-xo-1.75/olpcbasics.fth
+++ b/src/app/arm-xo-1.75/olpcbasics.fth
@@ -6,7 +6,6 @@
 
 fl ../arm-xo-1.75/addrs.fth
 
-: third  ( a b c -- a b c a )  2 pick  ;
 fl ../arm-mmp2/lcd.fth
 
 [ifdef] dcon-scl-gpio#