general: do not free strings gotten from getenv(), to avoid a crash

Signed-off-by: Marco Diego Aurélio Mesquita <marcodiegomesquita@gmail.com>

src/history.c

@@ -271,7 +271,6 @@ bool have_statedir(void)
 
     if (xdgdatadir != NULL) {
 	statedir = concatenate(xdgdatadir, "/nano/");
-	free(xdgdatadir);
     } else
 	statedir = concatenate(homedir, XDG_DATA_FALLBACK "/nano/");
 

src/rcfile.c

@@ -1258,7 +1258,6 @@ void do_rcfiles(void)
 
     check_vitals_mapped();
 
-    free(xdgconfdir);
     free(nanorc);
 }