add mexta field to simplify detection of overwrite

Because this invalidates existing save and bones files,
an increment of EDITLEVEL will accompany this.

include/mextra.h

@@ -75,6 +75,7 @@ struct fakecorridor {
 };
 
 struct egd {
+    unsigned parentmid;   /* make clobber-detection possible */
     int fcbeg, fcend;     /* fcend: first unused pos */
     int vroom;            /* room number of the vault */
     coordxy gdx, gdy;     /* goal of guard's walk */
@@ -92,6 +93,7 @@ struct egd {
  **     formerly epri.h -- temple priest extension
  */
 struct epri {
+    unsigned parentmid;   /* make clobber-detection possible */
     aligntyp shralign; /* alignment of priest's shrine */
     schar shroom;      /* index in rooms */
     coord shrpos;      /* position of shrine */
@@ -118,6 +120,7 @@ struct bill_x {
 };
 
 struct eshk {
+    unsigned parentmid;   /* make clobber-detection possible */
     long robbed;          /* amount stolen by most recent customer */
     long credit;          /* amount credited to customer */
     long debit;           /* amount of debt for using unpaid items */
@@ -145,6 +148,7 @@ struct eshk {
  **     formerly emin.h -- minion extension
  */
 struct emin {
+    unsigned parentmid;   /* make clobber-detection possible */
     aligntyp min_align; /* alignment of minion */
     boolean renegade;   /* hostile co-aligned priest or Angel */
 };
@@ -165,6 +169,7 @@ enum dogfood_types {
 };
 
 struct edog {
+    unsigned parentmid;       /* make clobber-detection possible */
     long droptime;            /* moment dog dropped object */
     unsigned dropdist;        /* dist of dropped obj from @ */
     int apport;               /* amount of training */

src/dog.c

@@ -27,6 +27,7 @@ newedog(struct monst *mtmp)
     if (!EDOG(mtmp)) {
         EDOG(mtmp) = (struct edog *) alloc(sizeof(struct edog));
         (void) memset((genericptr_t) EDOG(mtmp), 0, sizeof(struct edog));
+        EDOG(mtmp)->parentmid = mtmp->m_id;
     }
 }
 

src/minion.c

@@ -21,6 +21,7 @@ newemin(struct monst *mtmp)
     if (!EMIN(mtmp)) {
         EMIN(mtmp) = (struct emin *) alloc(sizeof(struct emin));
         (void) memset((genericptr_t) EMIN(mtmp), 0, sizeof(struct emin));
+        EMIN(mtmp)->parentmid = mtmp->m_id;
     }
 }
 

src/priest.c

@@ -20,6 +20,7 @@ newepri(struct monst *mtmp)
     if (!EPRI(mtmp)) {
         EPRI(mtmp) = (struct epri *) alloc(sizeof(struct epri));
         (void) memset((genericptr_t) EPRI(mtmp), 0, sizeof(struct epri));
+        EPRI(mtmp)->parentmid = mtmp->m_id;
     }
 }
 

src/shknam.c

@@ -561,6 +561,7 @@ neweshk(struct monst *mtmp)
     if (!ESHK(mtmp))
         ESHK(mtmp) = (struct eshk *) alloc(sizeof(struct eshk));
     (void) memset((genericptr_t) ESHK(mtmp), 0, sizeof(struct eshk));
+    ESHK(mtmp)->parentmid = mtmp->m_id;
     ESHK(mtmp)->bill_p = (struct bill_x *) 0;
 }
 

src/vault.c

@@ -27,6 +27,7 @@ newegd(struct monst *mtmp)
     if (!EGD(mtmp)) {
         EGD(mtmp) = (struct egd *) alloc(sizeof (struct egd));
         (void) memset((genericptr_t) EGD(mtmp), 0, sizeof (struct egd));
+        EGD(mtmp)->parentmid = mtmp->m_id;
     }
 }