Increase the value range of corpse weights

This breaks save compatibility, but is being pushed together with
other save-breaking changes to avoid the need for multiple bumps to
EDITLEVEL.

include/permonst.h

@@ -64,8 +64,8 @@ struct permonst {
     aligntyp maligntyp;         /* basic monster alignment */
     unsigned short geno;        /* creation/geno mask value */
     struct attack mattk[NATTK]; /* attacks matrix */
-    unsigned short cwt,         /* weight of corpse */
-        cnutrit;                /* its nutritional value */
+    unsigned cwt;               /* weight of corpse */
+    unsigned short cnutrit;     /* its nutritional value */
     uchar msound;               /* noise it makes (6 bits) */
     uchar msize;                /* physical size (3 bits) */
     uchar mresists;             /* resistances */