add the git prefix to the long version output

Tested on MacOS, written and not tested for Linux, not attempted for Windows

src/date.c

@@ -29,6 +29,7 @@ struct nomakedefs_s nomakedefs = {
     "Version 1.0, built Jul 28 13:18:57 1987.",
     (const char *) 0,   /* git_sha */
     (const char *) 0,   /* git_branch */
+    (const char *) 0,	/* git_prefix */
     "1.0.0-0",
     "NetHack Version 1.0.0-0 - last build Tue Jul 28 13:18:57 1987.",
     0x01010000UL,
@@ -125,6 +126,9 @@ populate_nomakedefs(struct version_info *version)
 #ifdef NETHACK_GIT_BRANCH
     nomakedefs.git_branch = dupstr(NETHACK_GIT_BRANCH);
 #endif
+#ifdef NETHACK_GIT_PREFIX
+    nomakedefs.git_prefix = dupstr(NETHACK_GIT_PREFIX);
+#endif
 
     nomakedefs_populated = 1;
     return;
@@ -161,6 +165,11 @@ free_nomakedefs(void)
         free((genericptr_t) nomakedefs.git_branch),
             nomakedefs.git_branch = 0;
 #endif
+#ifdef NETHACK_GIT_PREFIX
+    if (nomakedefs.git_prefix)
+        free((genericptr_t) nomakedefs.git_prefix),
+            nomakedefs.git_prefix = 0;
+#endif
 
     /* values are Null now; dynamic vs static doesn't really matter anymore */
     nomakedefs_populated = 0;

src/version.c

@@ -58,6 +58,10 @@ getversionstring(char *buf, size_t bufsz)
                      "%sbranch:%s",
                      c++ ? "," : "", nomakedefs.git_branch);
 #endif
+        if (nomakedefs.git_prefix)
+            Snprintf(eos(buf), (bufsz - strlen(buf)) - 1,
+                     "%sprefix:%s",
+                     c++ ? "," : "", nomakedefs.git_prefix);
         if (c)
             Snprintf(eos(buf), (bufsz - strlen(buf)) - 1,
                      "%s", ")");